Chapter Text
Sirius comes to them in the middle of the night.
He's drunk.
James stayed up, aware that it might happen. He has expected something like this since his best friend told him about his plan. Sirius was beside himself when he heard Regulus hadn’t been seen in months. The relationship between the Black brothers was fraught, but they loved each other. He could never have left the matter alone, and his reckless decision to come back to Grimmauld Place for the first time since the fight between him and his mother in their sixth-year was proof of that. James supported it. He knew Sirius wouldn’t be able to sleep at night until he had answers. And so he let him go and waited, ready to pick up the pieces.
Sirius manages to look graceful even when completely sloshed, James notes, admiring and a little concerned. He sprawls on their couch with the air of a man who is carrying the weight of the world on his shoulders, glassy eyes raised to the ceiling and a leg propped on the cream-coloured back rest. Lily murmurs something about putting the kettle on, and James would normally tease her about her seeming aversion to water-boiling charms, which she claims make the water taste tingly, but he is more preoccupied with shuffling Sirius so his head rests on James' lap, as shielded from the world as he can make him.
"I checked the tapestry," says Sirius after a beat of silence during which Lily has set two cups of jasmine tea in front of them and taken her seat on her favourite armchair, an ugly brown leather monstrosity that she inherited from her grandparents. James is petting Sirius' head like he does when his best friend is in dog form, watching the man's death grip on his bottle of firewhiskey and the redness of his eyes with apprehension, "Reggie's dead." He takes a shuddering breath, and continues. "That's not all, though. There's a new Black heir at Grimmauld."
James blinks.
"But—" he starts.
"Father was in no state to beget an heir," completes Sirius. He closes his eyes tightly to keep the tears from spilling. James rubs a thumb over his left eyebrow. "I know. He's the Dark Lord's." James gapes. Sirius laughs. It's a harsh sound, devoid of humour. James raises his head and makes eye contact with Lily, who is just as shocked as he is. She has her wand in hand, pointed at the tea cup she's almost spilled to the ground at the revelation. Sirius' laugh turns into a cackle, his blank gaze gaining a manic light. "Mother fucked You-Know-Who!" he exclaims and takes a swig of his firewhiskey.
"That's mad," says James numbly.
"Isn't it?"
Try as he might, he can't wrap his head around it.
You-Know-Who is objectively an attractive man, yes. Sharp jawline, well-defined brows, an evenly-proportioned face. He's tall and lean, with windswept hair. His irises are also stained blood red by dark magic, his skin unnaturally pale and his bone white hands could pass for claws under the wrong lighting. James would know, he's one of the few people who's survived a duel with the man. Lord Voldemort smells sickly sweet, like rotting pomegranate. He cannot imagine fucking that. The very thought makes him want to gag.
He supposes that would not deter someone as unhinged as fucking Walburga Black, who is just as much a calamitous beauty as the dark lord. Now that he thinks of it, Sirius has inherited that from her. He's all predatory grace and allure that could lead a man to his death, but without the cling of dark magic he looks more human than Walburga does. With an edge of something feral, yes, but without straying into uncanny valley territory.
"Father blood-adopted him before he died," murmurs Sirius. "I don't know what Mother said to convince him to do it. They named him Antares Salazar Black."
"Terrible name, that."
Maybe a nickname would help. Ant, maybe. No, that's terrible. Arry? That might do. Ares is a bit grim for a baby. Though he cannot imagine Walburga Black calling a child she's named Antares Salazar something as plebeian as Arry.
Sirius raises his bottle in agreement and takes another drink. "He'll be your son's age. They might even go to Hogwarts together."
They both pause when Lily abruptly stands up.
"I'm going to check on Will," she says.
James cranes his neck, silently asking for a kiss. Lily's eyes flicker to his lips. She walks up to him and, after a second of hesitation, pecks him on the cheek. He frowns, but does not protest. She can kiss him wherever she wants. He'll not force her to give what doesn't come willingly.
(He does not notice the raging fire burning in his wife’s eyes when she leaves the room.)
"Did you hear it all from Kreacher?" he asks once he's stopped hearing the sound of feet climbing up stairs. He distantly thinks he'll go up soon to check on their child as well.
Will is a handful. He's been crawling for a few months and decided to make it everyone's problem. James thanks Merlin for baby-monitoring charms. He would not have survived the year without them.
"No, Mother told me. She asked that I come back to Grimmauld. She wants me to raise the kid if she dies."
His expression twists then. James' hand stills in Sirius' hair. He cannot claim to understand Sirius' relationship with his mother. They love each other, he knows.
But sometimes love isn't enough.
Sometimes a child of the House of Black makes friends with a muggle neighbour before he is of Hogwarts age. Sometimes this child floos back early from a visit to his grandparents' estate because he wanted to pick something up in his room and show it to his grandmother, and he watches his beloved mother who dotes on him torture his friend as his father reads in the same room, unbothered. Sometimes he grows up and he can neither forgive nor forget, so he Sorts into Gryffindor and fractures the once loving relationship he had with his parents. His little brother never understands why this child is suddenly rebellious and hateful of the family he was once proud of, and their relationship shows cracks too, until the divide is so great they end up on opposite sides of a civil war. And when the child is sixteen, his mother hurls abuse at him for being caught having sex with a muggle-born boy and he has enough.
He screams back and she points a wand at him. When he flinches as if expecting to get hit, she lowers it and he runs to his room, packs up a bag and leaves, intending never to return. His best friend welcomes him home, and he'd call him brother if the child didn't already have one, and he would share his parents if it was that easy to replace a family.
(He would have done all this and maybe regretted it when he woke up with Sirius sleeping on his chest, his breath tickling his collarbone and a strange heat in his gut.
Before Lily deigned to look at him without disgust, there were lingering glances and unsaid confessions between them. Now there is a firm friendship that could withstand anything and a strange reluctance to call each other kin.
Brothers do not look at each other like that.
Lily knows, and it's fine, because she had her Mary and her Severus when he had his Sirius, and maybe she doesn't have either of them anymore, but she remembers what it's like.)
"Will you do it?"
"What's the alternative? Mother wouldn't have asked if she didn't think she'd be dying soon. Kreacher can't take care of him alone, and I won't give him to the Dark Lord or anyone of that lot."
James doesn't know how to feel about that. This situation doesn't seem real to him yet, the sequence of events so absurd he can only think of it with detachment. He sets it aside for now. Better to think of Antares Black as Sirius' brother than give himself a headache trying to think through the implications of Voldemort being a father.
"I'm surprised Walburga won't," he comments.
"She's less keen on him now that she's figured he's the reason Regulus died. At least she has some sense," he murmurs bitterly.
James sighs and makes a grabby motion at Sirius' bottle, who hands it to him. He takes a swig and savours the burn of the firewhiskey, opening his mouth slightly to let the smoke out in a regulated stream. He pretends he does not see the way his best friend's eyes linger on his throat as he swallows.
"Well," he says, "welcome to fatherhood, I suppose. But you're not a brother-father quite yet, so let's get roaring drunk tonight and figure it out tomorrow, shall we?"
Sirius' eyes look less empty than they were when he arrived, which is, as far as James is concerned, a victory. He takes back his bottle and groans.
"Did you have to make it sound like that?"
James blinks innocently. "I don't know what you mean."
"Brother-father, honestly. Gross, Prongs."
Lily hasn't slept well in a year.
She keeps having nightmares of her baby being mutilated by Death Eaters as she can do nothing but watch, of Voldemort coming to them in the middle of the night and slitting his throat with a mad grin on his bloodless lips. It never stops. Her mind conjures countless gory scenarios and she wakes up screaming every other night, haunted by visions of her child being murdered and all too aware that this might be her reality one day.
Sometimes, she cannot bear to touch Will.
She can only stare at him with empty eyes as he gummily grins at his mother and puts a foot into his mouth, hazel eyes crunching in pleasure, his messy red hair sticking up everywhere. She stares unblinking like he might disappear if she doesn't, and when she finally musters the courage to press a hand on his chest to hear his heartbeat and convince herself he's safe, her hand shakes with violent tremors. It scares Will, who cries bitter tears. The sound always makes her flinch, and she has to call James to help her soothe him to sleep while feeling quietly terrible about her failures as a mother.
And when she was having sleepless nights worrying about the prophecy that marked her baby for death, Lord Voldemort was getting it on with Walburga Black.
Today, she presses her child's face into her neck and listens to his mindless babbling, and all she can think of is how dare he.
How dare the would-be childkiller who torched her parents' home to draw her out of hiding have a baby when he is seeking to kill hers?
He keeps taking and taking from her. First Severus, then her childhood home, her parents, her friends. So many people in the Order died opposing this madman, and her son is his target. She's had to postpone her Potions mastery because of the war and she doesn't know how many years she and James and the Longbottoms will be made to hide, unable to live normally until the threat is over.
"Why shouldn't I take things from him too?" she murmurs, looking down at the small body pressed against her.
She holds Will tighter against her chest and summons a parchment, dicta-quill and a bottle of ink. She does not even have to think about who will be the recipient of her letter.
"Dear Severus," she enunciates, bouncing Will on her hip. "You have asked for my forgiveness, but I cannot promise to grant it. What I can do, however, is grant you the opportunity to atone. I have found a way to save my son, but it will require me to take measures James will never agree to. If you still regret our friendship, you will..."
Sirius stands in the wreckage of the Potters' home, blinking in disbelief.
He has not been back here in weeks. Not since Antares was stolen from St Mungo's after Mother brought him for a check-up. Sirius spent dizzying days trying to figure out where he was taken, by whom, and why. He would have been at it today as well if James, who was at Grimmauld researching with him, hadn't curled into himself like someone punched him in the gut and told him the inner wards of Godric's Hollow had ben breached. They had rushed out of the townhouse then, apparating as close they could.
He steps inside the ruined home, trailing after James who has ran up the stairs. His best friend makes a keening sound, more akin to that of a dying animal than to anything a human could produce. Sirius lurches to hold onto him before he sways, and they make the trek up the ruined staircase. It takes a handful of seconds to reach the nursery. When they do, they see Dumbledore is already there, inspecting the wreckage. His wand is drawn. He is performing some kind of diagnostic spell.
There is some initial confusion before Sirius explains that Wormtail was the Secret Keeper, not him, then the headmaster turns back to his readings.
Sirius doesn't care, his hand is on his best friend's shoulder as he picks up his godson, who sports a freshly-healed cut on his face, then turns back to kneel in front of his wife's corpse. It takes a long time before they are both in the proper state to listen to Dumbledore, who tells them what he thinks happened and asks that they bring Will to him in a week to check him for lingering traces of dark magic.
"Voldemort is not gone for good, I'm afraid," the old man says, "but it will take him a long time to recover his strength."
It should thrill him, thinks Sirius. The war is over, at least for now. The Death Eaters will scatter and they'll have to round them up, make sure no one tries to continue the Dark Lord's work. Sirius will go after Peter and avenge Lily. He'll help James raise Will. They must grieve, but they can also rejoice at the thought that his godson has survived the unthinkable. But Sirius can only think about Antares, disappeared who knows where, who has lost his father and will soon lose his mother too.
He can only muster a nod at Dumbledore, who takes his leave shortly after with a promise to handle the Ministry. James has not said a word this whole time. Sirius tries to keep him grounded, but there is nothing he can do when James abruptly bends to put his forehead against the crown of Lily's cold hair, hiding Will at the crook of his breast.
His best friend, the love of his life makes a horrible sound as he pours out his grief into the world, and it is echoed by the cry of a squirming child who had a harrowing night and is much too young to understand what happened. Sirius looks at Lily's body blankly, and frowns when it starts to shift in front of his eyes.
"James..." he starts, and shakes his friend's shoulder. "James, that's not Lily."
It is only when James uncurls, bewildered, and watches the corpse shift from young woman to middle-aged man that Sirius looks down at the toddler in his arms and hisses, "Antares!"
James and Sirius watch each other, uncomprehending, as his little brother pushes his best friend away to crawl into his own lap, relieved to see a familiar face.
Sirius absently curls his hand around the child's head and tries to make sense of this. James is better with numbers than he is. That is why he excelled in Transfiguration and Arithmancy, and why he was always the fastest at calculating the distance between stars for their astronomical charts. Sirius is no slouch either, though. If things aren't adding up, he can only surmise that he's been making the wrong calculations. And so he must adjust, and start counting again.
Voldemort is gone. He cast the Killing curse at his own son, who was disguised to look like William Potter, one of the two children potentially named in the prophecy. Antares' survival is likely related to him being the Dark Lord's blood, an instinctual rejection of Voldemort's attempt to harm his own heir by his own magic instead of the love sacrifice Dumbledore was theorising about.
A man was disguised to look like Lily, and he could not have entered the house without being given the secret by the Secret Keeper. Sirius looks down at the corpse. His features are familiar, and it takes only a moment to place them. That is Snape's father, he realises.
Lily is nowhere to be found, and so is Will. Someone made the switch while they were away looking for Antares, who disappeared shortly after Sirius told James and Lily about him.
He can see the same realisation dawn on his best friend, whose horrified expression would have told him all he needed to know about the man's culpability even if James hadn't spent the last few weeks helping him look for Arry when he should have been with his wife and child, all too aware that telling anyone else about him was not an option.
"He's a baby, James. He's my little brother," whispers Sirius, his eyes wide as he processes the depths of Lily's betrayal. "How could she?"
"I'm so sorry, Sirius. I'm so sorry."
This time, it is James' turn to ground him as he holds a child in his arms. When they separate, it takes them several attempts to conjure a Patronus message to meet Lily, the happiness necessary for the spell difficult to muster in the circumstances. When she arrives with Will in her arms and Severus Snape at her side, her expression twisted in grim satisfaction and no small amount of guilt, James' shoulders sag at the sight of his son then draw back up when he looks at her face.
To his credit, Snape retreats half a step behind Lily, his expression solemn at the sight of Sirius on his knees in front of his father's corpse, clutching the little boy he helped kidnap. Sirius chooses not to question it. He is too exhausted to provoke Snape into anger, no matter how much he might want to after getting confirmation that the man played a role in the events of that night.
"I did it for Will," says Lily, tilting her chin up.
She does not apologise, and Sirius would not want her to. Distantly, he understands where Lily is coming from. It does not mean he will ever forgive her.
When Sirius found out about his little brother, he did not know what to think. The thought of his mother sleeping with Voldemort while his own father was bedridden was too upsetting to think about, and learning about him in the same breath as learning about Regulus' death hurt like a knife in the heart. Sirius hadn't even remembered he had come into his childhood home like a thief in the night under James' invisibility cloak, and had confronted his mother without a thought for the consequences. She hadn't even screamed, which was unusual of her. She had only looked at him with tired eyes and told him he ought to come home.
Sirius hadn't wanted to, but he did. He came home and visited the silver-eyed child in the nursery room under the watchful eyes of Kreacher, then took tea with his uncharacteristically quiet mother, not uttering a single word until the cup was empty and he said his goodbyes. Sirius once thought he would never love another human being as much as he loved James and Will Potter, but he had been proven wrong. Antares took as much space into his heart as his best friend and his son do, as much as Regulus did until Sirius disappointed him enough time for that love to fold into itself in the hopes that it would hurt less.
It had given him and his mother common ground, which they hadn't had since he was nine. She had not taken Antares' disappearance well, especially not when she held herself responsible for it. He hadn't known how to tell her it wasn't her fault. He doesn't know how he will tell her it's actually his. Will Sirius ever stop trusting the wrong person?
"It was your right," he acknowledges. "A son for a son, you thought, I'm guessing? But Antares is more than Voldemort's son. He's the heir of House Black. My little brother," he emphasises.
Snape sneers. It seems he can't help himself. "Since when do you care about your House? They disowned you, didn't they?"
He shrugs.
"Judging by your choice of polyjuiced placeholder, I suspect you know that family is more complicated than that. My grandfather did not remove me from the succession, and Mother welcomed me back home to celebrate the birth of my little brother. The little brother you kidnapped, if I read things right. You're lucky Mother is bedridden, but don't count on that lasting. I've half a mind to curse you on her behalf. You know it would be deserved, Snape, but I suppose I did try to kill you a handful of years ago. I'll call us even, but you're on thin ice. Lily, though? You're dead to me."
Snape clenches his jaw, visibly biting back a few choice words. Lily only nods, pressing a kiss to Will's crown. Her eyes are on her husband. Sirius wants to claw them out of their sockets. How dare she look at him when she betrayed them both?
"I want a divorce."
Sirius whirls around, staring at James. The words were said quietly, but loud enough for Lily to hear them. There was no hesitation in his voice, only resignation. When Sirius turns back, he sees the same feeling echoed on Lily's face.
"Alright."
They part ways after that. There isn't much more to be said, only a quiet agreement to split custody, a vow from Lily that she wouldn't harm Antares again and another from both conspirators not to tell another soul about his parentage. They all agree that the truth about the switch should be kept quiet, and it is Lily's responsibility to justify her own survival to Dumbledore. Sirius takes James back to Grimmauld and lets him sleep in his childhood bedroom, then takes his brother to their mother. He gives her an overview of what occurred in quiet words. She commands him to kill Lily, and Sirius is sharply reminded of why he left. When he refuses, she screams and screams and screams until her voice is hoarse, then grows despondent, refusing to respond even to Kreacher's coaxing.
In the next few days, Sirius takes care of James, of Antares and of his mother in equal measure, and pretends he doesn't see the latter poring over books of dark arts in search of the best way to curse the woman who stole her child. Sirius will not kill his godson's mother, but he will not get in the way of Walburga's retribution. When James tells him some time after that Lily's womb rotted inside of her and had to be removed, he does not pretend to be surprised. He feels no satisfaction from it, but he won't begrudge his mother this. James gives him a searching look, but says nothing of it.
Things get more complicated when the Daily Prophet proclaims Will Potter as the Boy-Who-Lived and Lily as the Woman-Who-Survived.
(Deep into the Department of Mysteries, a prophecy fractures. The future, for better or for worse, is now uncertain.)