Archive of Our Own

The door swung shut, hopefully for the final time.

"Well," Rosalind said, watching it from their perch on the lighthouse stairs, "are you satisfied now?"

Silence for a long moment, long enough that she glanced to the side to see if Robert had heard her. His gaze stayed pinned to the lighthouse, and even in the poor light she could tell that his frame held a tightness that indicated he was on edge. Perhaps he expected the door to fly open again and DeWitt or the girl or both to come tumbling back out.

When the door stayed as it was, his shoulders relaxed. "Quite satisfied, I think. And you?"

She lifted her hands a little in a gesture of surrender. "All right. I will concede that in this case you were correct and I was not."

"Thank you." He gave a little half-nod, half-bow of acceptance.

"Though you must admit that my hypothesis was equally sound, given the data available."

"More sound, you used to say."

There was no sensible reply she could make to that, so Rosalind didn't bother, but took another step upwards and craned her head to look at the circling light above.

The rain pattered against rock and timber, seemingly less fierce now. The lighthouse's beam swung through the air once, and twice, and a third time.

"Well," Robert said. "What next?"

"'What next?'" she said, looking back at him. "Do you mean to tell me that you gave no thought at all to what we'd do if you succeeded?"

He looked not at all startled by her annoyance. "Of course I did. I simply hadn't settled on anything concrete. Besides, the choice should ought to be yours."

"What, am I now to have a say in our activities?" Damn, that had come out a bit more cutting than she'd intended.

"You aren't going to be a sore loser now, are you?" His expression grew a touch wounded.

"No," she said, still too sharp, and made herself wait and soften her tone before she answered again. "No. I'm glad to have the whole mess over and done with, that's all."

The wind had grown less intense, and the rain was definitely beginning to slacken into a drizzle. She took another few steps upwards, tugging off her hat as she did so. She wasn't likely to have much need of it from now on, and for all that it and her raincoat had served her well, she'd begun to loathe the sight and feel of them. There'd been news of a volcano kicking up a fuss in the far northwest; it might be wonderfully cathartic to go there and rid herself of the blasted things by heaving them into the lava flow.

Atop the staircase, she tugged their note free from the door and let the wind carry it from her hand. "Hard to believe it's all finished, really. Do you think the whole set of timelines will collapse an instant? Because if that's about to happen, I'd prefer not to be on this rock if--"

"Rosalind," he said.

She turned.

His mouth was set in the odd way that meant he wanted to smile, but was attempting not to. "I do appreciate you sticking with it, more than I can say." He held out his arm. "If I might indulge in cliché, I couldn't have done it without you."

She hadn't heard him speak that way, in a tone both pleased and serious, for far too long, and the sound of it made her press her lips together to hide her own smile. "That’s utter nonsense. You could have and, if you recall, were perfectly willing to attempt to do so."

"Very well. I wouldn't have wanted to do it without you." He crooked out his arm.

"Hmm." She allowed the corners of her mouth to curl up a millimeter. "In spite of making you row every time?"

"In spite of that."

"Well, I appreciate you saying it." She tapped her way down the steps to stand with him, hooking her arm around his and linking their fingers. Even with the chill of their locale, his hand was warm. "I suppose it is better to have things this way, in the end."

"And he wasn't the worst test subject we've ever had," Robert said. "Even entertaining in some cases, wasn't he?"

"That depends on your view of entertainment." Much of the humor had paled for her by the thirtieth or fortieth go-round, but Robert had never quite failed to be amused at the repeated spectacle DeWitt’s first flailings along the skylines, or his tumbling through the tower's ceiling and subsequent pelting with books, or potted plants, or whatever the girl happened to have close to hand when he arrived. "Rather frustrating, too. And a bit dim--to the point of fatality once or twice, if you recall. I do think we could lay a good number of the failures squarely at his doorstep."

"I still don't understand all the trouble we had with the shield infusion."

"Unfortunate chemical reaction with something he'd ingested, most likely." Rosalind wrinkled her nose. "We did see him eating out of garbage cans fairly often."

"True. I suppose it's too late to go back and investigate further."

"Yes, by now it's a moot point. Do let's close the topic and move on."

'What next' indeed, she thought, as they descended the stairs. Like Robert, she had made no allowances for this result, though she'd had a much better reason. Why plan for what wouldn't happen? She’d had a bone-deep conviction of how it would all play out--either Robert would tire of the whole experiment and they would find a much more worthwhile endeavor on which to expend their energy, or they would run through the process again and again until one or both of them went mad. Even when significant variations had begun popping up in this most recent iteration, she'd prepared herself at any moment for yet another stumbling block to appear, leaving them to return to the beginning and make preparations for number one hundred and twenty-four.

Yet here they were. No more rowboats in the rain--really, no more rain at all unless they chose it. They might go where and when they pleased. An infinite number of worlds, and all the time they would ever need to see what was in them.

It was tempting to let her mind exult in all those possibilities, but she drew herself out of it with a little shake of her head. Practicality must come first. Their formal research had been neglected for far too long in order to keep running DeWitt through his paces, and while freedom to go wandering through and between universes was a marvelous thing, a completely vagabond life would not make a suitable state to launch any study of science, especially in a field as delicate as physics. There was a need for a stable environment, in both the physical and the mental sense. No matter what grand plans or lofty heights one aspired to, it was best to reach for them with a bit of solid ground (so to speak) under one's feet. And now their familiar residence with its convenient kitchen-and-parlor-turned-laboratory would vanish along with Columbia.

Still, there were plenty of places where the two of them might set their feet.

"I am thinking," she said as they reached the bottom of the stairs, "of a house."

"Are you?" Robert said. "So am I."

She bumped his shoulder with hers affectionately, pleased to find their minds in tune. "Something a bit larger this time, perhaps."

"And not so elbow-to-elbow with the rest of the world."

They began to make their way down the dock.

"You know," Robert said, as the boards creaked under their footsteps, "as pleasant as our house was, I really cannot say that I shall miss Comstock's atrocious statues cluttering up the landscape. The one of you--of me--of us wasn't so bad, but the rest--"

"On that, dear brother," she said, "we are quite agreed."

They stepped off the dock, and away.

One winter in her late girlhood, Rosalind had returned from an afternoon outing with a slight cough. It began as an almost unnoticeable thing, but within a week it had turned thick and bone-rattling, leading her mother to fretfully confine her to bed and dose her with tisanes and syrups.  Rosalind's health as child had been fair, but her constitution was not robust, and the Streptococcus pneumoniae took root with fervor, producing a battery of fever and chills and shortness of breath. She had a clear memory of lying awake in her childhood bed staring dully at the pale blue and white strap-work of the wallpaper for a long stretch of hours, too tired to turn her head from where it listed on the pillow. She had thought at one point, with an early touch of the cynicism that would become second nature to her in later years, that dying in this drawn-out manner was going to be a dreadful inconvenience and she would have much preferred it to be over with quickly.

That had been the worst night. The next day she found breathing to be fractionally easier, and the next day easier still. By degrees the infection dissipated, and Rosalind mended. She spent a great deal of that winter in bed, but was up and about again by early spring, and with a head full of theories from all the reading she had done while propped up amongst the pillows.

Years later she knew (if only by logical conjecture) that, as with so many events, the outcome of her illness had not been set in stone. It had been but a point at which the path of her life split. For another Rosalind the ordeal after that long night was worse yet, as was the night after that. The thickness in her lungs lingered, refusing to be dispelled by any efforts of care or medicine, and grew worse until there was nothing more to be done. That girl remained in her bed until the evening the sheet was finally pulled over her head and now-breathless lips, and the world spun on without her.

That universe is where she and Robert chose to settle, for while the personal details are a touch morbid, the resulting circumstances are ideal. The death of her counterpart in this timeline has cleared a space for herself and her brother to exist without interfering with the timelines of any of their other selves--unless they choose to, of course. Their branch of the family had been smallish, and with her counterpart's parents deceased as well, there is little chance that any would object or call notice to the addition of an interloping pair of R. Luteces to the world.

Laying the foundations for themselves proved not so difficult as she had feared. Too much direct interaction with the normal population was still a chancy proposition, but many of the necessary arrangements could be made by letter and by telegraph. Money, no longer essential to their survival, still an unfortunate necessity in establishing certain matters of stability--and yet that too was a problem easily solved. When one was no longer strictly bound by the rules of the physical world, the acquisition of all sorts of things became much less of a challenge.

They took a house, white-painted and dark-roofed, already furnished, on enough acres of property that there would be no neighbors to gossip about any lengthy absences or the keeping of odd hours. In size it could well be described as 'rambling', certainly large enough that this time whatever devices they might choose to build need not swallow up half of the building this time.

Not that she would begrudge the space, if it were necessary, but it would be pleasant to no longer worry about stumbling over generator cables if she were up and about in the middle of the night.

Rosalind had of course considered suggesting that they make a great leap forward, twenty or fifty or a hundred years, if only for the sheer novelty of seeing what sorts of advancements the field of physics might make. For the moment, though, she found the thought of remaining in their current time suited her best. She had never yet found anything that quite matched the thrill of a moment of a breakthrough, whether it was the slow-dawning revelation that came after months of work or the lightning flash of a sudden epiphany. Perhaps at some point the potential scientific advancements of the future would beckon more strongly, but until then, why skip too far ahead and deprive herself and her brother the pleasure of first discovering such wonders for themselves?  In her own mind, she had even begun to tentatively consider the possibility of publishing again. Of course their theories were a touch too advanced for the world as it stood at this point, but a paper or two, or a book, might serve to lay the groundwork, and at the same time provide an interesting experiment in itself of just how far their influence on a thread of reality might extend.

That, however, would require a proper foundation of data and argument on which to build. The bulk of their recorded observations had vanished into nothingness along with their laboratory, and would need to be reconstructed and re-documented--irritating, but not impossible. Furthermore, their most recent experiment had produced a wealth of data that could, now that they had some peace and quiet, be evaluated and hammered out into their proper expression and scientific theory.

That is what they set their minds to.

It has all the trappings of a mundane, isolated existence, yet Rosalind could not describe it as anything other than as both fantastic and fantastical. Though she disliked the comparison, she found it akin to the period after Comstock had plucked her out of her laboratory. At that time it had been both exhilarating and surreal to find herself no longer constrained by third- and fourth-rate equipment, by lack of support, by the prejudices of colleagues. The feeling now was the same, only multiplied a hundredfold. She might never again achieve the public renown the came from setting a city amongst the clouds, but she now possessed the ability to study the construction of the universe--of all universes--in astonishing detail, an eternity in which to do so, and the ideal partner with which to do it. They calculate, and analyze, and argue pleasantly, and she makes Robert move around the heavier furniture until they are both satisfied with the arrangement of every room.

She cannot imagine a more ideal existence.

Of course, given the established law of entropy and the less well-established law of universal caprice, such a state could not continue indefinitely.

She couldn't say with certainty what month it was, or what day, since in their situation the habit of keeping track of such things fell by the wayside, but the hands of the parlor clock stood at 2:23, and a glance at the darkness outside window further clarified that it was late evening or extremely early morning.

They had learned early on--in the midst of pushing the tenth DeWitt through those early steps to Monument Island--that while the human brain was marvelously adaptable, even a state such as theirs could not alter it to the point that working at full capacity for thirty or fifty or seventy hours without respite was a possibility. In life, they had possessed the dubious benefit of physical weariness to remind them that they were exceeding their capacities; now she found they must rely on subtler warning signs. She and Robert would pause in conversation only to realize that neither was quite sure what exactly they had been discussing, or she would finish a page of equations and look them over to see that halfway through the Σs grew teeth, the psis looked more like pitchforks than proper Ψs, and lines she had thought were ruler-straight instead twisted in bends and loops across the paper.

Perhaps there was some simpler way of addressing the problem, but until they discovered it, they relied on the straightforward solution of allowing themselves periods of mental relaxation. Occasionally they even fell back upon the traditional restorative of sleep, though she felt that this was not exactly the proper name for it--she has not dreamt since her ‘death’, and Robert reported much the same. She would recline, close her eyes, let her thoughts fall into nothing, then some space of time later open her eyes and arise with her mind fresh and all its parts apparently back in working order. They spent an afternoon wrangling over other potential terms ("Stasis?" "Hiatus?" "Lacuna?" "That'd be a bit pretentious, wouldn't it?") before deciding that the entire argument was rather pointless.

Yet this evening--or morning--their minds were not quite so enervated as to be in need of sleep. They had adjourned from their work some time ago, and wandered towards the parlor, and eventually slipped into quietude, soothed by quiet and the glow of warm lamplight off the cream-colored walls. She had been idly picking out the Consolation No. 3 on the piano but had let her fingers fall still halfway through, propping one elbow on the edge of the keybed. Robert had a book in his lap which he had ceased to read some time ago in favor of apparently meditating on some point in midair.

Rosalind ran her hand in gentle drift over the top of the keys, watching as Robert's hand turned a page while he continued to ignore the book.

She straightened and tapped out a C in 6th--1046.50 hertz, not shrill but still excellent at drawing a person's attention--and watched him blink himself out of his contemplation of the wall.

"Is something wrong?" he said.

"I certainly hope not," she said. "However, you've been looking thoughtful and worried in equal measures for quite a while now."

"Have I?" he said, visibly trying and failing to arrange his look into one of innocent unconcern.

"Yes," she said. He never could remember that his mask was not nearly so good as hers. "And the likeliest possibility is that you're going to propose an idea you think I won't like." She tilted the cover back over the keys with a quiet thump. "Say whatever it is and let's have it out now."

"I’d hate spoil the evening if you’re going to take it badly."

“Is my bad opinion that fearsome?” She set her folded hands on the cover in an attitude of calmness. "Whatever it is, I promise to be open-minded."

He flipped the book shut and set it aside, obviously squaring himself up.

"DeWitt and the girl," he said. "I think we ought to see how things played out for them. Any of them. If you're amenable, that is."

"Well," she said. The suggestion was not exactly a surprise. Though she had been content to ignore it, the thought had occurred to her too, and now that Robert had brought it up she had little excuse for continuing to dodge the issue. Much as she wanted to dig in her heels at the thought of spending any more time on those two, DeWitt and the girl were, in a sense, the products of an experiment. One did not eliminate an entire series of timelines without causing immense fluctuations, and having expended so much effort on the entire enterprise, it would go against scientific principle not take an interest in the various outcomes. And it would please Robert, and keep him from fretting.

"All right," she said. "But I'd prefer that this not lead to more endless rounds of attempting to correct whatever mishaps they might have stumbled into.”

“Fair enough,” he said. "I promise to rein in any impulses to meddle."

Her confidence in the validity of that promise was not high, but it was kind of him to make it.

What they find both was and was not what she expected.

In more than one universe they are obliged to witness outcomes that, while less destructive in a large-scale sense than the fiery obliteration of New York, are no less disheartening. The death of DeWitt's wife, though not a universal constant, still occurred more often than not, and as a result DeWitt is nearly always at a mental and emotional disadvantage when it comes to caring for his newborn daughter. Many times they watched him make a long, slow walk down 68th to leave a blue-wrapped bundle at the doors of the foundling hospital, then turn to go back into the streets alone. More often than not those girls went west by train, to a thousand different fates; by that time DeWitt was usually dead of drink or close to it. Other times he clung to the girl, yet remained too broken by his wife's death and burdened by debt and alcohol to rise to the challenge of raising a child. Sometimes DeWitt died while the girl was still young, leaving her to be swept off to an orphanage or to scrape together a living however she can; sometimes the girl went first, struck down by illness or bad food or the choking air of the tenement that her father could never find the energy to escape.

Yet in just as many universes presented a turn that would be well-suited to any two-penny moral tract, in which the continued presence of a daughter altered DeWitt into something of a capable human being and parent. The stretch of time between his wife's death and his daughter's first birthday remained a long downward slide of bleakness and dissolution, but there came a point he slowly but surely began to climb back up--poured a bottle after bottle of alcohol down the sink drain and took whatever work he could get to scrape together funds. Father and daughter are, of course, still subject to accident and weaknesses of character and the accumulation of unfortunate variable outcomes that so many people call 'bad luck', but an astonishing number of them manage to scrape out a life that would, by any standards, be called 'happy'.

A particular point of interest was the girl herself. Though psychological analysis was somewhat outside of her métier, Rosalind could not help but be intrigued to find that many of the girls who were now Anna mirrored several of the traits of the girls who might have been Elizabeth. Even without the confines of a cage, a significant number showed a predilection for puzzles and ciphers--a happy confluence of events, since the years of the girl's mid-twenties would provide several choice opportunities for a young lady with a talent for cryptography. A similar amount retained an interest in the arts, in which Robert is more qualified than she to judge the girl's talents--although, the tastes of the art world being ever-changeable, neither of them can truly be certain in their predictions of success or failure in that field.

"This one's moving in an avant-garde direction, isn't she?" Robert said, eying a row of canvases scattered across the little studio the girl had taken. All the artistic DeWitt girls they had observed had so far adhered to traditional styles, but some influence had clearly spurred this one down a different path, resulting in a studio of paintings that began as comprehensible landscapes and still lifes and shifted, piece by piece, into swirls and whorls of muted colors.

Robert tilted his head at the girl's most recent work, still on the easel. Blue and grey daubs spun haphazardly from edge to edge. "What do you think it's meant to be? 'Pebbles on the Sea-shore'?"

Rosalind, noting down brief descriptions of each piece, spared it a glance. "'Bird Pursuing Its Prey', surely." She scribbled another line.

"Bird?" He leaned closer.

"See, there are its eyes--" She pointed. "And that's the curve of its wing."

"That's a wave, and those 'eyes' are clearly rocks."

"How can they be rocks? They’re clearly ocular in nature."

"They’re obviously--wait a moment.” He’d pulled the canvas forward a little from the easel. “She’s written something on the back…oh."

"What?"

"'Pigeons by the Seine'."

"Ah. I should have known.” She flipped the notebook shut. "As interesting as this all is--"

He arched an eyebrow at her.

"--Yes, yes, I do admit it. But we are rather limiting ourselves by sticking to just these two."

He let the canvas fall back into its setting. "Are you suggesting that we widen our field of observation?"

"You needn’t look so surprised." She folded her arms. "If we’re going to engage in this, we might as well be thorough about it."

 "Well." His face turned thoughtful. "Who do we start with, and when?"

There was, of course, an obvious first choice of persons whose existence they ought to take interest in. Already they had seen traces of her handiwork, Anna or DeWitt saved from this or that accident, and inexplicable reunions between father and daughter in timelines where events ought to have separated them.

Given the circumstances, however, they both agreed decided that in this case discretion—namely, avoidance--would be the wisest course of action.

"After all," Robert mused, as they discreetly observed the girl as she watched seaweed float past a window, "she's likely able to take care of herself at this point."

"Near-omnipotence does not necessarily qualify one for self-sufficiency," Rosalind said, but let the matter drop. When a girl’s presence set the very atoms of a universe vibrating in strange and unusual ways, it was best not to attract undue attention from her unless absolutely necessary.

That option eliminated, there remained a no shortage of subjects for them to observe.

They riffle through a multitude of lives. The woman who might have been Lady Comstock continues to break hearts in droves; in some universes she does indeed prove to be the mother of Anna DeWitt, and in others she is not. If he survived that long, Cornelius Slate always ends up in the Boxer Rebellion and always loses an eye, sometimes serving for years afterwards and sometimes ending his life by his own hand. Preston Downs dies peacefully of old age in Montana or falls prey to a tiger in India. They made an extended and fruitless attempt to locate the little girl who so often sent letters to both Rosalind and Elizabeth; apparently the undoing of Columbia had erased her entirely. Even Daisy Fitzroy--that began as a pursuance of curiosity, as a weather-watcher would follow a bank of storm-clouds to see if they would spin themselves into a tornado, and soon proved just as wide-ranging as the path of any true cloud. Daisy Fitzroy roamed hither and yon, to Baltimore, to Philadelphia, to Chicago, or out of the States entirely, and when they could locate her, they found that upheaval nearly always followed in her wake. But just as many times they lost track of her entirely, and eventually found that the threads of her lives spread too far and wide to presume any sort of consistency.

And then, many turns later, the two of them sat at a particular table in the Palm Room of the Waldorf, on a night that the table ought to have unoccupied. Rosalind’s ears were filled with the clink of silver and china and glass and the muted buzz of surrounding conversations.

"Is he looking yet?" She'd let Robert take the seat facing the room this time. Being on watch hindered one’s appreciation of a meal, she'd found, and since they weren’t likely to make it past the fish course she ought to get as much enjoyment out of what she did eat as possible.

He lifted his head a little to peer across the room. "Not yet. Remind me, when did this one last see us?"

"A year ago, in Pennsylvania. That steelworkers' strike."

"That recently? I wonder if we ought to space these out a little more. Not that I mind having an evening out--" His fingers brushed the points of his tie, knocking it askew by a millimeter.

“Do stop fussing with that,” she said, reaching across with one hand to straighten it properly.

His hand dropped back to the table. "—but do you think this is petty of us?"

"Not particularly. Our visiting '29 half a dozen times to watch him jump out the window was petty. This provides us with a chance for a subtle bit of revenge and--" She deftly sliced a spear of asparagus in two. "--an excellent meal."

The look he gave her was dubious. "A meal from which we don't actually receive any physical benefit."

"We can derive a sense of gustatory satisfaction." She took a bite to demonstrate the point. "And a pleasant memory."

"That's going to depend on how this fish has turned out," he said, contemplating the square of sea bass he'd pinned with his fork.

"If you'd try it, you'd know. Mine is excellent." Though she couldn't blame him for the hesitation, as their situation did occasionally make the consumption of a meal an unintentional mental distraction. The flip of a coin might have two (or perhaps three) potential outcomes, but a single dish had a thousand times that amount, and while she and he might only be able to perceive one universe at a time, when one was so vividly aware of the existence of others it was all too easy to lose oneself in the tangle of splitting timelines and contemplating potentialities. Was the sea bass that the fisherman hooked a fine specimen, or the less ideal one swimming next to it? Was this year's spring a dry one or a damp one, and how did that affect the vegetables? Did the saucier sleep poorly or well last night? And if he slept poorly, was he so bleary-eyed this evening that he bumped into the poissonnier? And if the poissonnier was jostled, was he irritated enough afterwards that he did not give his full attention to the fish he was preparing?

Robert eyed the fork for another second, then brought it to his mouth.

"Well?" she said.

He shrugged. "All right. It is pleasant."

"As I said. Should we look yet?"

"Wait a moment--yes, now."

They shifted in their chairs, Rosalind letting her face slide into an aspect she knew to be both disapproving and piercing.

Across the room, Jeremiah Fink, in good spirits and gregarious, turned address a remark to one of his dinner companions. Something caught his eye (a glint of light? the fluttering of a palm leaf?) and he turned further, and then, quite by chance he was looking in their direction. Recognition washed over his face, and he paled, pinned by their eyes.

They held his gaze for just the right length of time--a trick they’d had to work out, how long to stare without disturbing the man enough that he’ll flee, or get his nerve up and attempt to confront them--and then, as one, she and Robert turned back to their plates.

“It certainly seems to be having an effect,” Robert said through a mouthful. To make up for his earlier hesitation, he was taking up bites of fish in haste in preparation for their exit. That, too, they’d learned early on: once spotted, it was best to quietly disappear a few moments later. "You do realize that by trying to kill us, the version of the man that we knew technically--"

"--did us a favor?” Rosalind swirled the last swallow of wine in her class. “Of course, in a backhanded and unintentional way. But it's the principle of the thing." If Robert had pressed her, she would have admitted that this whole endeavor was rather petty of them--after all, none of these versions of the man had been responsible for any slight against them. Still, Columbia's absence hadn't improved the man's morals, his business practices, or his tendency to profit unfairly from the physical or intellectual labor of others. She let the crispness of the wine spread over her tongue, and felt a sort of serene satisfaction at the thought that no matter what successes Fink might achieve or what end he came to (shot; stabbed; self-defenestrated; crushed in a particularly hideous traffic accident; and, irritatingly, even sometimes dying in bed of old age), innumerable versions of him would go through life on the edge of uneasiness, haunted from youth till death by two unknown figures with red hair who appeared at unexpected moments out of the corner of his eye or in the corner of the room, watching and never speaking.

They did not, of course, spend every moment side by side. It took a little effort to break the habit sticking close together, and too long a separation still left Rosalind feeling vaguely unsettled, but common sense dictated that to refuse to leave each others' company at all was foolish. If a train of thought called to mind a study that Rosalind had read once during her schooling, she might take fifteen minutes to return to that particular library and avail herself of the volume without dragging her brother along with her. If Robert felt peckish and wished to spend half an hour selecting the perfect just-ripe apple from a Washington orchard, there was no need to disturb Rosalind from her calculations for him do so.

Therefore she was not overly surprised that there came a point when she walked downstairs one day, late in the morning, to find an empty house and a note in Robert's blocky handwriting tacked to the frame of the workroom’s chalkboard.

Dear sister, it read,

I have stepped out elsewhere briefly on a small errand. If I have not returned before you read this, then I shall certainly be back soon.

She shook her head a little at its brevity. Well, his absence was no reason not to commence on their work; she could have it ready for him to look over and add to when he returned. The chalkboard itself was only half-filled and trailed off in the middle of an equation, marking the point where she and Robert had retired yesterday. Rosalind corrected a poorly-scribbled symbol with a few swipes of her fingertip, then began to fill in the latter half. Every now and then she stepped back to evaluate the whole, rolling the chalk in the palm her right hand. The mental exercise of running through equations and contemplating polynomials, sine and cosine, ∂ and ω and Ψ was so pleasantly cerebral that she barely felt her perceptions of the rest of the world drop away into nothing.

Eventually, after too long pondering the placement of a variable she shook herself out of her trance of contemplation and saw that the shadow of the side-table by the window had shortened enough to just touch the tip of her shoe.

Her stomach gave an odd sort of dip, a sensation that she recognized as the beginnings of concern. That meant that she had been staring the board long enough for the light from the eastern window to have shifted a great deal. It must have been...three hours? Perhaps longer? She was far out of the habit of calculating time in the ordinary way as it related to herself, but clearly more time had passed than she had realized. And though she and Robert had had more than one debate over the imprecision of verbal colloquialisms as they related to lengths of time, she was quite certain that an absence of three hours did not fit either her or his definition of 'back soon'.

Well, immediate alarm was not a sensible course of action. She would attempt the most obvious potential solution first.

‘Elsewhere’ would mean a universe besides this one, so she called to mind a handful of timelines and points of existence, and then began skimming her way through them, a microsecond at a time.

Jeremiah Fink splattered onto the pavement yet again. Sixteen-year-old Anna DeWitt twirled to show her father the curling feathers on her new hat. Daisy Fitzroy stepped out of a Georgia prison, shading her eyes from the sun with her hand. Booker DeWitt held out a racing form for his little daughter to peer at; she wrinkled her brow childishly at the list of horses and, after some consideration, touched the name “Hindus”. Fink toppled backwards, clutching at a blood-stained carpet, the knife his mistress had stabbed him with still caught between his ribs. Daisy hunched against a wall on a July night in Chicago, gasping to catch her breath before she started running again. Anna perched at desk overflowing with papers, clicking her way through a cipher device with one hand and scribbling notes with the other. DeWitt sat in the side room of that dingy office, staring into the crib. Daisy turned a street corner, leading her daughter by the hand, the red ribbon in the little girl’s hair fluttering behind her in the breeze. In Paris Anna turned away from a half-finished painting of a shadowy seascape to look over her shoulder--Rosalind met her glance, and saw the girl's eyes go wide in the split second before she disappeared.

Robert was nowhere to found in any of them.

Back in their own workroom, she realized that her limbs had grown tight, as though some part of her brain was forcing her to hold extremely still. She wanted to take a steadying breath, even though she no longer required any sort of respiration. There was no definite reason to be concerned, or for her to go bounding through universes like a frightened rabbit. This delay must have some logical explanation. Likely he had—had...

Her brain refused to offer up a suggestion--in fact, she almost felt it floundering after one. She had not worried over anything in some time, and had forgotten how the upswell of reactions generated by the chemical response to stress could hamstring any efforts at rational thought. Not surprising that in this state she had been caught wrong-footed. Adrenaline? How interesting, some small part of her mind was saying. Does mean our nervous systems are still functioning in some way, in spite of our condition? I really ought to be recording the details of this....

She took a few steps backward and sank carefully into a chair. Millimeter by millimeter, she forced herself into calmness. There must be a solution--if only she could apply her mind properly--

The note was his, assuredly. That handwriting could not be mistaken. And she could think of no person or force that could induce him to leave a false note before his departure.

She dismissed out of hand the idea that he was staying away deliberately. There was no reason at all to consider it. Even if he had conceived on his own some sort experiment to test any potential effects of a temporary separation--no, he would never attempt such a thing without her knowledge. To do thoughtlessly would have been callous, and deliberately would be cruel; he was neither. Equally unlikely was the possibility that he had simply stayed away longer than he’d meant to. Robert could be prone to distraction, yes, but no matter how long he spent elsewhere, there should be nothing to prevent him from returning to whatever specific point in time he’d intended.

She let facts and conjectures spin through her head while the shadows on the floor lengthened.

The first hypothesis that emerged was one that she had thought proven unviable: the death of all Comstocks and erasure of all Columbias might very well result in the erasure of their selves as they were. With no city in the sky and no trans-dimensional device, there would have been no tear for Robert to step through in the first place, and thus their meeting and all subsequent events would have never occurred. Perhaps the two of them would have blinked out like candle-flames, or perhaps they would have snapped back to some previous point, unknowing of the future they had lost. It had been an obvious potential outcome of their experiment with DeWitt and the girl, yet neither she nor Robert had spoken aloud of it before, or during, or since. By his determination to see the enterprise through she assumed that he had accepted the possibility, and therefore she was forced to do so as well; with the venture concluded and the two of them still clearly in existence, there seemed to be no need to address the issue.

If it were to happen, she had thought that it would happen instantly--but time and space have proved more than once to be slippery, tricky things. Perhaps the ripple of their actions had only now caught up with them? By that logic it ought to have reached her as well, though. Is there some quirk that would erase her brother, yet allow her to continue to exist and remain unmoored in the universes?

The thought chilled her.

The second hypothesis was less horrific, though still unpleasant to contemplate. Wherever and whenever his errand had taken him might have held some danger that prevented him from returning. She could not imagine anything that could damage or imprison them in their condition, but it was not an impossible proposition. If that were the case--where and when would he have gone? What would he need to see that could pose any threat to him?

She sat, pinned by indecision. The house was utterly still, and that stillness began to press in upon her. She had forgotten how the quality of silence in a place changed when one was truly on one’s own; when the other person was not simply in a different room, or down the road, but utterly and entirely absent.

Eventually the silence and the absurd paralysis of her situation became so grating that she found herself standing, and then drifting towards the gramophone in the corner. A few turns of her hand, and the opening notes of the Gymnopédies floated through the room as she began to gather up stray pens, and sort through rolls of diagrams and half-finished sheets of notes. Their workroom, while not entirely topsy-turvy, tended to remain in a shifting state of untidiness. Sitting and forcing herself to labor at the problem head-on was not succeeding; she would allow her brain occupy itself with a different sort of input and output for a while and let the bits of data in her head tumble together however they pleased.

She was standing on tiptoe to return a book to its shelf when the idea slipped itself upwards and into the forefront of her mind.

Rosalind stood motionless, fingers pressing into the cloth of the book’s spine, and ran mental fingers across the thought, probing it for weaknesses. Not an different hypothesis, but one that mingled elements of the two she was already considering. There was nothing about it that made particularly likely to be the correct solution, but nothing about it contradicted the facts she already possessed. At the very least, it was a thought that ought to be investigated.

Ascertaining the truth of it, though, would require help from another source.

She slipped the book back into its place with a single motion, then walked swiftly out of the room and to the hall closet. Their raincoats, which had been spared by laziness from her idle thought of volcanic death, still hung at the back, and—yes, what she sought was still in the front pocket of hers. She and Robert had taken turns disposing of that lighthouse-keeper in Maine; the last turn had been hers, and afterwards she’d slipped the pistol into her raincoat’s pocket without a second thought.

Now she drew it out and gave it a considering stare. Not that she was likely to need it, but given the choice between over-prepared and under-prepared--

Especially considering where and when she was about to go.

She tucked the pistol away in her coat. Undue attention indeed, she thought ruefully, and blinked away.

The table was tucked into a curve of the wall, somewhat sheltered from the bright light of the promenade. Bubbles rose upwards outside the window. The bar across the way had propped both its doors open, and the music playing was a relentlessly cheerful tune, loud enough that even at their table outside Rosalind could hear the singer exulting I'm in love, I'm in love, I'm in love, I'm in love, I'm in love-- One chorus and it was already beginning to wear on her nerves.

"Don't you find that irritating?" she said.

"Haven't been here long enough for it start bothering me," Elizabeth said, slipping a cigarette out of a thin silver case. "From what I can tell, you just have to get used to it. People love their music here just as much as in Columbia." The girl had been staring moodily into a half-empty glass of clear liquid and ice and had reacted to Rosalind's appearance in the seat across from her with nothing more than a blink and a slight shift of her plucked eyebrows. She was all gloss now, her skirt cut slim, her mouth painted red, a glint in her eye of the same blue sharpness of an electrical arc. How a fledgling's plumage could change once it left the nest.

"You know, Madame Lutece," the girl said, shutting the case with a click, "I wasn't expecting to see you again after that last turn in the rowboat." She slipped the case into a dainty black handbag and drew out a matchbook, Kashmir printed across it in bold letters."Should I be honored? I didn't think you were the type to make social calls. Not on me, at any rate."

Rosalind eyed the cigarette in the girl's hand. Your father would have a fit of apoplexy if he saw you, she thought. Any version of him. "That's a correct impression."

The girl struck the match alight. "Meaning you're here for a reason."

"Obviously." She could already feel a headache beginning to form behind her right eye. She was out of the habit of carrying on conversations with others, and even if she were not under the pressure of her task, even if she and the girl were exchanging pleasantries instead of engaging in this uneasy discourse, she would not want to be here. Rapture set her teeth on edge, and even Robert, though fascinated with the ingenuity it had taken to build such a place, had found it unnerving on the whole. Every city was a mass of disasters and dangers and accidents barely averted, but this place was rotten through with catastrophe. For every rivet that stayed tight, there was another that loosened; for every pipe that held, another burst and began to flood the tunnels with ice-cold sea-water. Not to mention the political and social tensions that were at this very moment on the edge of boiling over.

The girl blew out the match and tossed it into the ashtray, then slanted back into the curve of the seat, one arm folded across her chest. "So? My time's not as limitless as yours, and I've got things of my own to do."

Trickery and obfuscation would do her no good here. Best to say it outright and be done as soon as possible. "I...am in need of your help."

Elizabeth huffed out a sound, halfway between a laugh and a scoff. "Oh, really? And you thought you'd just drop in and ask for it straight out? After what you did to me?"

Not a promising start. Well, Rosalind had expected a certain amount of hostility. "While I admit to my part in it, you can't intend to lay the blame for the entire scheme at my feet."

"The idea might not have been yours, but certainly provided the method, did you?" She waved a hand expansively, trailing cigarette smoke. "Did you think I'd forget how much of it you were responsible for?"

"No. And therefore, I would hope that you remember the efforts I took to undo it."

"And you think that makes up for it?" Incredulity laced every word. "Just because now it never happened doesn't change the fact that it did happen. And it'll have always happened to me, because it's in here." Elizabeth tapped a finger against her temple. "Besides, I heard your voxaphones. You'd've left me where I was and spent the rest of your life watching atoms crash into each other while Comstock put his leash around my neck. You only did it because your brother put his foot down."

Rosalind pressed her tongue against her the back of her teeth. "Then since this concerns him as well, you might do me the courtesy of listening."

The girl's hand, moving to flick the ash off her cigarette, paused in its path. "Does it," she said, with a flat sort of interest. "I had wondered where he was. Not like you to break up your double act."

A school of angelfish swam past the window, dappling their table and the girl's face in shadow for a moment.

"All right," Elizabeth said, sitting a little straighter. "Let's hear it."

Rosalind told her.

It seemed to take very little time at all to lay out what she knew, and the much less certain elements that she only suspected, yet by the time she had finished the ice in glass had shrunk to thin circles and girl's cigarette, smoldering away, was near to ash.

"And?" Elizabeth said.

"And--?"

"That's everything?" The girl settled back again. Her glaze ran over Rosalind's face, and settled at last on her eyes. "I still don't see why I should to help you, or what it is you need me for in the first place. If you already know where he is--"

Rosalind shook her head. "I have a...a conjecture which fits the facts as I have them. That narrows down the search somewhat. But I cannot perceive things as you do, and for me to hunt through every possible universe one by one is not a feasible option."

"Why not? You've got all the time in the world, don't you?" The girl blew out a stream of smoke, blue in the underwater light. "All the time in every world?"

"I do not." A little of the smoothness slipped away from Elizabeth's face at the vehemence of that last word--her eyes a touch wider, her mouth parted a little in surprise--and Rosalind pressed forward before the girl dropped back into indifference. "Imagine--" She grasped for an appropriate metaphor. "Imagine there is a word in your vocabulary that has become so intrinsic that you cannot remember how to converse or read or even comprehend the world without it. One day you find that the word has been removed from your mind completely. If you possessed one million volumes of one million pages each, and were certain that the word you required existed on a single page in one of them, but knew not which volume or which page--" 

Elizabeth was not looking at her face any longer. She was looking at the table--at Rosalind's hand on the edge of the table, which had clenched into a white-knuckled fist.

Rosalind took a breath and made herself let go. “I have the time and ability, yes. What I fear is a lack of resilience in my own mind. I might chance upon the correct universe and place and time right away, or it might take me a length of time I would perceive to be a year. Or ten. Or a thousand. Much as I would like to believe that I have the mental fortitude to search for that length of time without going mad, I cannot help but be realistic.” She met Elizabeth’s gaze squarely. “But it’s is a challenge I will accept, if you refuse me. I had to seek you out first, no matter how hostile you might be. I could not ignore the chance for an immediate solution.”

She fell silent.

The girl reached for her glass, its ice now melted entirely. The crack in her mask was gone, but she looked less cold now, and more thoughtful.

"I'll tell you what." She spun the glass slowly in her hand, her fingers leaving dripping trails in the condensation. "I don't think I owe you anything. But I'll help you with this, and later on, you and your brother can owe me a favor."

Rosalind let her expression shade into sardonicism. "A favor to be named at a later point, of course."

The girl half-shrugged, the roll of one shoulder. "Who can say what I might need help with in the future? But I don't think our aims are likely to be that far apart. Deal?"

There was no point in considering, or even in pretending to consider; both she and Elizabeth knew that she was going to agree. Still, she took a few seconds to let her mind run through all the possible requests this sharper, hard-edged Elizabeth might ask of them, before pushing herself back from the table. “Very well.”

"All right." Elizabeth brought the glass to her mouth and downed the contents in a single swallow, then slipped out of her seat. "Let's go."

She led the way, her heels clicking rapidly. A few occupants of other tables glanced at Elizabeth; a greater number turned their heads to blink at Rosalind, their puzzled eyes flicking at her too-long grey skirt and out-of-date hairstyle.

A little way down the promenade lay a set of double doors.

“This’ll do,” the girl said, resting a hand on one door as she turned back to look at Rosalind. "I'm guessing you can get yourself home?"

“Whether we can or cannot,” Rosalind said, “I’m certain you’ll know where to find us when you wish to call in your favor.”

That pulled something almost like a smile onto the girl’s face. She nudged the door and let it fall open an inch, then stepped to the side. “Take care, Madame Lutece.”

“I would remind you to do the same,” Rosalind said, “but I’m already certain you will.” And then, belatedly, “Thank you.”

The miniscule space between door and door-frame revealed only blackness. Rosalind pushed the door open, and stepped through--

--into a hallway.

There was no physical dizziness--it truly seemed as though she’d moved through any ordinary doorway--but she still felt a brief rush of disorientation.

Was how the one hundred and twenty-third DeWitt had felt during the end, walking over and over into places he had already been? She knew this hallway, she had seen it nearly every day of her life before she had left her parents' home, for that was what this place was, and--she glanced over her shoulder--yes, behind her was the bedroom where she had studied and slept and dreamt, and where other Rosalinds had expired on a winter's night.

A room greatly altered now, however. The bed and clothespress remained, but all the other furniture had disappeared, even the bookcases, and the room's occupant had stacked books and notebooks into a knee-high maze of neatly ordered towers. She took few steps away from the door and peered up and down the hallway. The lighting was poor—the curtains had all been pulled and none of the lamps were lit--but from what she could see of the other rooms, they had been similarly denuded of furnishings. The hallway wallpaper, pale green with twining branches, was spotted with rectangular faded patches.

Not decisive evidence, but all good indications that her conjecture had been correct.

The disorientation did not fade as she made her way to the staircase. Everything felt at once larger and smaller than she remembered it. With no furniture to muffle them, her footsteps echoed oddly. And there was another sound--a low humming that was familiar, though at a pitch some degrees lower than she recalled. The sound of several generators working together.

The humming grew louder as she descended the stairs, her hand sliding down the smooth wood of the handrail and curving around the newel post as it had a thousand times before.

Downstairs too showed signs of depredation, the hall tables and knick-knacks gone and the walls stripped of adornment. The parlor, she saw, was shut tight, and a brief twist of the doorknob confirmed that it was locked, but even without crouching, she could see a faint glow under the door.

Her adrenaline spiked again, pushing her to batter down the obstacle, or to simply shift along the possibility space until she was inside the room.

Patience, she thought, and made herself continue further back into the hall. The door to the sitting room was shut as well, but the dining room stood open; as she came closer she eased the pistol out of the pocket of her, letting it hang loosely in her hand.

In her memory the room had been somewhat spacious, even with the long table and its array of chairs and the dark wood sideboards covered with delicate vases and china. Now it was at once bare and cluttered, stacks of paper on the floor in the same neat and orderly rows as the books in the bedroom, the only remaining furniture the table and two chairs sat at its leftmost corner. One of the chairs was piled with papers, which had apparently migrated upward from the floor.

The other chair held a woman, head bent over a notebook, a cup and saucer at her elbow.

Rosalind stood in the doorway, . She made no sound, but something must have drawn the other woman’s attention, for she lifted her head--

--her head. Her face. Rosalind’s face.

Rosalind felt an odd sort of laugh bubbling up in her throat, half shock and half satisfaction--I was right, she thought--and squashed it back down.

"There you are," the other Rosalind said, rising from her seat. She had blinked on first seeing Rosalind in the doorway, but her look had been one of mild startlement, not true surprise. Now her face smoothed into placidity. "I knew you'd be along eventually. Of course I had hoped it would be later rather than sooner, but I suppose one can't have everything." Her eyes went to the pistol at Rosalind's side. "You do realize that isn't necessary?"

"I certainly hope it shan't be," Rosalind said. "However, I've found that having one gives an excellent sense of just how serious the possessor is." She stepped through doorway. "Where is my brother?"

"He's unharmed, I assure you." The woman had come around the side of the table and begun shuffling at the chairful of papers. Once they had been knocked into neatness, she scooped them up and deposited them on a mostly-empty spot on the table.

"That doesn't answer the question I asked." Rosalind took a step closer to the table, then another.

"He's in the parlor. What used to be the parlor, I should say; there isn't much left of it now." She dropped into the now-paper-free chair and inclined her head towards the other one. "Do sit, please. I'd very much like to speak with you for a moment. Robert has told me all sorts of remarkable things."

Rosalind stared at her for a long moment, her skin prickling with alertness. The worry had faded and been replaced by a serene sort of anger, burning white-hot. The less rational part of her wanted very much to shoot this woman now and be done with this entire absurd situation.

Instead she sat in the offered chair, keeping the hand with the pistol uppermost in her lap.

"Forgive me for not offering you any coffee." The other Rosalind drew the cup a little closer to her. She appeared quite calm. "I’m already running low. You do find me in somewhat distressed circumstances."

"So it seems." Rosalind said. Now that they were closer, her already-overworking mind had caught on her counterpart's appearance. When she had first seen Robert, in spite of the disparities in their overall makeup, her mind had immediately fastened upon the all tiny similarities in their physical appearances: the blue of their eyes; the set of their jaw; the bend of their fingers. With this counterpart, all Rosalind could see were the differences. She ought to appear younger, and yet the circles under her eyes were more deep-set, the lines of her skull seemed more pronounced. She looked older than Rosalind knew she herself had at the moment of her death.

No, not older--worn was a more accurate descriptor. Rosalind had spotted that look in her own mirror quite often, in the days before Robert and before Comstock. She had never been able to devise a name for it other than ground down, the face of a person with the sense that they were dragging themselves down a path that would never lead anywhere. She had not seen it on herself in many years, and never to this extent, as though the expression had been borne so long that it had settled deep into the flesh and bone of its wearer.

“I gather,” she said, “that your path was quite different from mine.”

“Perhaps only on a few points, but I’m sure we both know how significant that can be.” The other Rosalind took a delicate sip of her coffee. “I did manage a minor success or two, but on the whole, my experiences post-graduation were rather disheartening. When my parents--pardon me, should I say 'our parents'?"

"I don't think the problems of grammar are particularly relevant at this point," Rosalind said crisply.

"As you like. The house came to me when they passed away, of course, and returning to it seemed like the best solution. At least here I have the space I need and may do what I like with it." She swept her hand to the side a little, indicating the proliferous stacks. "I grew tired of being edged out of laboratories, and fighting for room and proper equipment was clearly always going to be a losing battle."

"I see," Rosalind said. "And you sold the furniture?"

“Obviously. I’m afraid that most of it’s gone now.” The other woman plucked a trailing thread from the sleeve of her shirtwaist. "I'm sure you're aware that when circumstances call for it, one really requirements very few luxuries. With my needs as they were so many unnecessary pieces sitting about, it would have foolish not to sell them off immediately. The rest went over time, whenever my funds ran low. The carpets will have to go next, I think--I did try to hold on to them to keep the place a touch warmer when the weather turns, but it's them or the tables, and I'm short of organizational space already." She propped her chin on one hand. "Every now and then I've been able to catch the attention of some potential investor, but the combination of a female scientist and a number of theories which, to them, sound exceedingly outlandish--"

"Yes," Rosalind said. "I do understand."

It was exactly as she’d thought. Their erasure of Comstock from any timeline in which he might have existed had sent her other selves and past selves careening down far different tracks than they might have followed. Even in his absence, there must have been universes in which Rosalind still managed to succeed--alternate sources of funding appeared--but there must have been an equal number in which her colleagues had judged her ideas to be worthless, and no patron had the bravery or open-mindedness to risk investing in a female scientist, and the answer, no matter how politely phrased, was always no and no and no. And within some number of those worlds should reside Rosalinds aware, even if only through inference, that the multiverse contained their ideal counterparts--but lacking the means to bridge the gap.

Apparently, this one had decided to rectify that problem. The anger stringing its way through Rosalind’s nerves began to glow hotter.

To steady herself, she flicked her eyes at the ramparts of papers and notebooks. "Clearly you haven't let those limitations lead to idleness."

The other woman laughed. "Would you? No, one goes on regardless, even when the going is hindered.” She set her cup on the table with a clink. "And between the furniture and the occasional windfall, I managed to scrape together enough funds to develop one or two advancements."

"As I thought," Rosalind said. "Those generators I heard are powering a Lutece Field?"

The other woman nodded. "Somewhat modified from your version of it, I suppose." She drummed her fingers against her notebook. "I haven't the resources lift a city into the sky, or even the smallest of buildings, but when one can suspend the motion of a particle, grand feats of levitation need not be the only end result. One might do very well just to hold a collection of particles in place. Even a person whose atoms are somewhat...oddly scattered. Not that that was my purpose for developing it, of course."

Rosalind sat back a little in her chair. "You weren’t expecting one of us, then?"

"Oh, not at all, though I did have a faint hope. The logic behind it was sound enough, after all. If one posits the existence of multiple universes, there must be other versions of myself, with the same field of interest and with a--well, a more fortunate path." The other Rosalind traced the rim of the cup with a fingertip. "Following from that, there would be the likelihood that one of those other versions would discover some method of transcending the barriers between universes, and therefore a possibility--slim, but not non-existent--that one of those might find their way here." She looked knowingly rueful. "It was simply unfortunate that the one who did was already attached elsewhere."

"Yet in spite of that, you decided to hold him here, well aware it would be against his will."

The other woman's mouth curved in a way that was not quite a smile. "You of all people know that I am not the sort of person to let an opportunity escape."

Rosalind gritted her teeth, but dipped her head, conceding the point. "And now?" she said.

“I would have liked to have a longer discussion with you, but I imagine you’re in neither the frame of mind nor the mood for it.” She set her notebook on the table and folded her hands in her lap. “However, I would like you to answer a question for me.”

“That question being?”

“As I said, Robert has told me a great deal. But I would like to hear your own thoughts on one point.” She leaned forward. “The mutability, or lack thereof, on past events. Do you think it is truly possible to undo what has already occurred?”

Rosalind felt her face begin to stretch into an expression of surprise, and fought to pull it back into blankness. That--was not a question she had been expecting. A multitude of words gathered on her tongue; it took her some effort to order them into a response.

“If you seek a decisive opinion, I’ve none to give you,” she began. “And if you’ve asked Robert the same question, I imagine he’s told you that it is. I’m also certain that if you’ve been speaking with him, you’ve become aware that he can be something of a tireless optimist about these matters.

“Which...is not to say that he is incorrect. We did, after all succeed in our aim, and have seen firsthand that the resulting changes are significant. On the other hand, you must consider the extraordinary lengths it took to achieve it. And you and I both know very well that one experiment proves nothing.” She spread her hands, one empty, the other not. “All I can tell you is that I once knew it to be an entirely futile endeavor, and now cannot think the same.”

She pressed her lips together. As an answer it lacked resolution, and to reply unsatisfactorily went against her sensibilities. Yet what else was there for her to say?

“I see,” the other Rosalind said. Her face was expressionless. “Thank you.”

She set a key on the table. “The parlor key,” she said. “The panel to shut off the field is on the sitting room wall; I’m sure you can work it out.”

Rosalind blinked. "Is that all?"

"Should there be anything else?" The other Rosalind had already begun to turn back to the table. "Even if you'd come here without the gun--which I still hope you aren't planning on using--there isn't any way for me to stop you, is there? I suppose I could refuse to surrender the key until we came to blows, but given your circumstances, any altercation would end with you the victor. If I'd had a few months to devise something, perhaps..." She paused, then shook her head. "As it is, well--for an afternoon I had an hour or two of intelligent conversation with people who understood me. That will have to be enough. I imagine some versions of ourselves will go through their lives without even that pleasure."

She sat back, leaving the key lay on the table between them.

There seemed to be nothing for Rosalind to say. Her anger, unexpressed, still pulsed through her, but now there was nothing for it to batter itself against. She could rage at the other woman for her temerity--how dare you try to do what you have done?, she could say--but what would be the purpose? Mingled with the anger was dull, hollow sensation she faintly recognized as pity, but if she were this Rosalind--if she had been her--any words of sympathy would only grate.

For one bizarre moment she thought of offering the other Rosalind the pistol and the chance to shoot at her, if it would make her feel better. It wasn’t as if it would do her any harm, after all.

Then she slipped the pistol back into of her coat, and took the key. It was cool in her palm.

"Goodbye," said the other woman, flipping open her notebook as Rosalind stood. "And please do tell Robert goodbye as well, since I don't suppose I'll be seeing either of you again."

"I doubt it," Rosalind said.

At the door to the sitting room she paused and looked back. Her counterpart's head was once again bent over her work.

Rosalind eased one foot over the doorframe, then the other. Then, half-turning to glance over her shoulder, she said, "However, I have been much mistaken in my predictions of late."

She saw the other woman’s hand pause in its scribbling, but she did not turn or raise her head. After another moment Rosalind turned away, and did not look back again.

The panels proved just as easy to comprehend as she had been told. Under other circumstances she would have loved to study the entire setup further, dig into wires, take everything apart and put it back together--it was a marvel that her other self had managed to jury-rig it all together under such straitened conditions.

But now she flipped the switches off and twisted the dials down to zero, and when the hum of the generators had died away, she turned the key in the lock and shoved the door open.

She had no idea if her perception of time and motion was overwhelmed by emotion or if she’d simply leapt instantly from one space to the other without knowing it, but in one instant she was standing in the doorway and in the next she was at Robert’s side, clasping him by the arm.

"It’s me," she said, and realized the second the words left her mouth it that it was a ridiculous thing to say.

"Of course it is," he said. He looked a little pale and drained, but otherwise seemed unharmed. "Are you well?"

A rush of mingled relief and exasperation washed through her. "Am I--? Are you well?"

"Perfectly well," he said. "Though it shan’t be high on my list of things that I’d care to repeat."

“How on earth—no, don’t tell me here,” she said. “I am not inclined to repeat this experience at all, and I’m past ready to leave.”

"I am also," he said. "Though it has been enlightening.” He looked towards the ceiling where cables met in a dizzying series of loops. "She’s done a great deal on her own, hasn’t she?"

"More than anyone would have thought possible, I suppose," Rosalind said. The other Rosalind had been right: there was very little left of the parlor as it had been. Windows boarded up, plaster and paneling ripped out, floorboards pulled up.... How much had she done herself? How much had she had to leave to hired workmen, to whom she would have had to say yes, this is want I want done to my parlor and yes, I do want that arc braced there and no, I am not interested in your thoughts on these blueprints?

"And--" he glanced toward the door "--how is she?"

Rosalind did not follow his gaze. "She is--as you’d think." And, gripping his arm a little more tightly, "I don’t think she’d appreciate a farewell from either of us."

"Ah." He turned back and studied her face; given her lack of control over her expression at the moment she had no idea what he saw, but it seemed to settle the matter. "You’d know that better than I."

"Then--"

"--let’s go," he finished for her, and with that they were back in their own parlor.

They stood together in the dim light. The familiar surroundings now felt a little jarring. She opened her mouth, closed it, opened it again. Her mind, irritatingly, seemed to have been knocked askew once more.

"We owe Elizabeth a favor," she rattled out, for lack of anything better to say.

"I wondered if you might decide it was worth the risk to ask her help." He face was inquiring. "She’s…all right?"

"Much changed in many ways," she said. "And in others, still exactly the same."

His brows drew together. "Is there a cause for concern?"

"I cannot say," she said. "I really do not know."

At that point her nervous system apparently decided that it would be ideal to sit down. Her knees wobbled, and let go, and she dropped ungracefully onto the sofa, her grip on Robert’s arm dragging him down to sit with her.

"Let us agree now," she said, her voice firm, "that the next time one of us goes off by ourselves, we will tell the other exactly when and where we intend to travel."

His eyes had taken on the downcast look of guilt. "I truly did think I’d be gone briefly—and the thought of this sort of situation occurring was so unlikely--"

"Really, a great deal of this could have been avoided if—"

"Rosalind," he said. "You're going to bruise my arm."

She let out a long breath. "We don't bruise any longer," she said, but she relaxed her hand, finger-length by finger-length, until she was no longer grasping him quite so strongly. “And your equanimity over this is a bit irritating.”

“I knew you’d work out what happened,” he said.

“You were certain of it?”

“Certain enough not to fear being trapped in that room permanently." His face was set with conviction. "Boredom seemed the most likely danger. And no matter how long I was there, she wouldn’t have harmed me, you know. Any more than you would."

"No," she said. "Which does not mean that, given sufficient time, she might not have done something worse." Found a way to do away with me when I arrived, she did not say, staring at her other hand, where it lay not quite clutching the folds of her skirt. Or some way to seal off a universe so that nothing else from outside could enter it--

She tamped that thought down. To linger over what might have happened would be to distress herself without cause. There was no need for it.

After a moment, Robert’s hand pressed against hers. "You will have to tell me how it all went, with Elizabeth and…her."

She glanced at him from the corner of her eye. He did look a little unsettled now. Whether or not he had worried for himself, the evidence of her concern had clearly affected him.

"And you," she said, "will have to tell me what this errand of yours was." Then, attempting lightness: "You might have let me know that you were going off to spy on some other version of myself. Ought I to be jealous?"

"You could take it as a compliment that I find you interesting enough to be inquisitive about every version of you."

"If I do, will you then take it as a slight that I don't feel compelled to do the same to you?"

"I wouldn't," he said. "Besides, it wasn't spying, it was only--"

"Curiosity?" she said, and then, "No, don’t tell me yet. I…I would just like to sit here for a while, if you’re agreeable."

"Yes," he said. "I’d like that too."

They leaned together, forehead to forehead, saying nothing, and listened to the parlor clock tick.

 Afterwards, they did very little for a length of time. They did not leave the house, but drifted from room to room, sometimes with each other, sometimes past each other, their conversations inconsequential and their work limited to small tasks. Robert finished the straightening-up of the workroom that Rosalind had begun; Rosalind found herself rereading foundational works on physics and some of her earliest notes. She could not say that she found it a pleasant mood to be in, but she recognized the necessity of it. They had been jarred, however briefly, out of their equilibrium, and there must be a period of adjustment and processing of events before they could settle into it again.

She was paging through a series of notes on probability theory when a thought occurred to her. A quick mental calculation of the past few days confirmed that she was correct, and she rose and wandered to the door of the workroom, where Robert was crouched on the floor untangling a series of charts that had attempted to turn themselves into a nest.

"It’s our birthday," she said, poking her head into the room. "According to the current local time and the system of calendar dates, at least."

Robert paused in his battle against too much paper. "Do people in our condition have birthdays?"

"I suppose that's up to us." She leaned against the doorframe. "Still, I thought you’d like to know."

He sat back on his heels and considered. "Have you idea of how old we are now?"

"Counted in linear time?"

“That’s the usual way of counting this sort of thing.”

"No idea at all," she said. "But in remembrance of the day, would you care to go out?"

Now he looked surprised. “Does your suggesting that mean that you already have somewhere in mind?”

“I do, as a matter of fact,” she said. “After that, you may choose.”

The landscape and greenery of the cemetery were well-designed enough to be pleasing to the eye even in winter. Unfortunately the section in which the Luteces of this universe were buried was located next to several families who had favored abundant scrollwork and melodramatically weeping angels to mark the graves themselves and their relations.

Still surrounded by hideous statuary, even in death, Rosalind thought. The headstone belonging to her youthfully deceased counterpart in this world did bear a pair of carved flowers in bud, but other than that was thankfully plain, with only the dates of her birth and death and a simple inscription.

"'Beloved daughter'," she read. "I suppose this one wasn't around long enough to truly be a trial to them."

"That’s a grim point of view to take," Robert said. "You were loved."

"Love does not preclude parents from looking at a child as though they’d expected something different."

"Ah," he said. "I understand." Off her pointed look, he continued, "Not quite in the same way, perhaps. But I did sometimes have the sense that Mother had secretly hoped for a daughter."

"And when she did have one, it was myself, and she still found herself disappointed," Rosalind said. "How unfortunate for her."

She considered the gravestone. "Do you think she was happy, in her time?"

"It's pleasant to think so," he said. "Though if you'd like to find out for certain, that's easy enough."

"No," she said. "I don't think it'd be the wisest idea."

There was no one else about. Like this it was easy to think that they might be the only two people in the world. Her brain began to offer up an observation: if two people who are neither dead nor alive stand in a cemetery--

She exhaled, watching the vapor in her breath condense and spin away into the whiteness of snow and sky.

"All right,” she said. “Now you may tell me."

He did not need a hint as to what she referred to. "It was only a whim," he answered. "A curiosity, as you said."

"About myself?"

"About what else you might have done, without Columbia. You did say we ought to be thorough." His eyes stayed on the ground, and he toed at a thin patch of snow, letting the grass peek through. "You’d never suggest it yourself, of course, but I thought you might like to know what else you could have achieved."

"Really," she said, letting the end of the word trail off inquisitively.

So they stood there for a while, and she let him fill her head with the other lives she might have lived: writing book after book;  teaching at Wellesley, half-terrifying and half-awing students year after year; speaking in front of the crowds at the Exposition Universelle, and afterwards walking by herself in contemplative bliss through the incandescent glow of the Salle des Illusions.

When he wound to an end, she took up the thread. "And after that you found a possibility that would have made for a less enjoyable recounting, which you ought to have expected to happen eventually."

"She was quite civil, and we had a perfectly amiable conversation."

"Right up until the moment she said, 'do come see what alterations I've made to the Lutece Field!' and shut you up in that room?"

"If you’re going to tell me it was foolish--"

"Not entirely," she said. "It was...thoughtful. And--well, I shan’t say you were right not to mention it to me beforehand, but if you had I likely would have dampened your enthusiasm by pointing out that you were almost certain to discover as many unpleasant sets of events as you were pleasant ones. Certainly there are ones even more disheartening than what we’ve already seen." She shifted, the snow squeaking under her feet. "Or some universe in which I did the sensible, proper thing and married instead of going to school--"

He looked rather horrified. "Surely not."

"It must have happened," she said firmly. "No matter how much you or I would like to think otherwise."

Robert scowled a little, and she elbowed him gently.

"It's the way of things," she said. "No one can be happy in every universe."

"Your elbows are too sharp," he said, but did not attempt to make an argument.

A gust of wind sent the tails of her scarf fluttering.

Now that her mind had come round to that topic, she could not push the issue away. She had not, in all her years of life or death, shed tears for whatever less fortunate versions of herself might exist. Now, ever since their return, her mind has been circling the images of those millions of other Rosalinds--and Roberts too, most likely, though perhaps not as many--who found themselves blocked, and frustrated, and unfulfilled, all their potential stymied by the confluence of circumstances. And her sharpest thoughts were of that other woman, forever leaning over a notebook in an empty house.

At some point far in that woman's future--perhaps in her late years, or after her death--the magnitude of her studies might be realized. Assuming that any of her research survived, of course, and didn't end up in a rubbish heap, and that whoever found was honest and not the sort to claim it for themselves.

Rather cold comfort, no matter how low one's expectations of accomplishment were.

If one were to intervene, when and where and how should it be done? What action would change the course of that one life, and the lives of the others that Rosalind knew must exist? A sudden windfall from an unknown source, a word in the ear of a potential investor--

No, she told herself. Absolutely not. It was one thing to observe a universe, or to give events the slightest of nudges, but she had not gone through endless amounts of trouble only to disturb her long-sought peace by endlessly meddling in timelines to benefit others, even if those others were her selves. The extent of their ability to influence the course of a timeline was still an uncertain quality, and considering the efforts it took to succeed last time--

--and yet, and yet, and yet...she can already tell that the thought has embedded its hooks too deeply to be dismissed, and is on the way to becoming one of those unsolved problems that occupies her mind to the exclusion of all else. It’s not as if the two of them lack for time or resources to experiment with, after all, and the possibility of success in this is certainly higher than in their last endeavor. And if the idea had occurred to her, it had likely already occurred to Robert as well. Perhaps even now he was thinking of it; perhaps in a universe that was splitting off from this one, he was even now beginning to speak the words to suggest it.

Perhaps this time, she might be the one to suggest it first.

For the moment, though, she kept quiet and let her thoughts turn. The cold and the quiet made this a pleasant place to think. She and Robert would stay there a little while longer, she knew, standing at the grave of her other self until the daylight began to fade. Then they would choose where to go next, and disappear, each leaving a single pair of footprints in the snow.