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Yuuta’s squeezing his way through a busy pedestrian side street in the sweltering summer heat when his Thread goes taut.
It tugs at his pinky, firmly enough to stop him in his tracks and turn him sideways. It digs in. It claws, like rough hewn rope tearing into his skin, far from the soft red yarn it appears to be.
“Yuuta-kun?”
A tentative hand settles on his shoulder. He shrugs it off, chest tight, eyes glued to the simple knot and bow tied around his finger. The Thread trembles under his watch, fraying at the ends, pulled and pulled and pulled until the loops of the bow start to shrink.
He feels it in his gut, pure instinct. Somewhere out there, a person Yuuta’s never met—his soulmate—is dying.
“No,” he chokes out. Threads are intangible, he knows, but that doesn’t stop him from trying, clamping his other hand around his pinky as if that’ll be enough to stop his soulmate from slipping away.
It’s not enough. All at once, his Thread unravels, spilling like fresh blood from his hands, and it hurts, not just in the flesh of his finger but in the very depths of his soul, heartbreak carved from his ribcage and dropped to the cold, unfeeling ground—
“Yuuta?”
He lets Rika-chan cradle him in her arms, hot tears streaming down his face, but he’s numb. This time, there is no body to curse into staying by his side forever, nothing but the slack coil of limp red string draped across the base of his finger, inaccessible to his cursed energy.
He doesn’t move. He can hardly breathe, irrational fear that he might jostle the loose Thread off his pinky and sever their tie for good freezing him silent as the grave. But the fact that the Thread hasn’t detached means that his soulmate yet lives, whatever pitiful state of life it may be, and Yuuta can do nothing but vow to keep vigil until their connection fades completely.
He’s vaguely aware of being herded off the streets and back inside his own room, where Miguel lingers at his doorway with an awkward kindness that he ignores. He can’t bear to turn his focus away, not now. Already, every blink to wet his tired eyes feels like the very moment he’ll miss his soulmate’s end. He can’t spare anything else.
Golden afternoon light dims into a pink and orange sunset swallowed whole by a moonlit night. Rika-chan stays with him, crooning wordless song soft in his ear, and his mind spins itself into spiraling circles over what must’ve happened to his soulmate to bring them so close to the edge of death and pin them there, helpless.
Was it another car accident?
Or was it, perhaps, a curse?
All he knows is that Yuuta should’ve been there with them. He should’ve saved them. He should’ve met them at the very least, surpassed the Thread’s limitations and tracked them down through sheer force of will alone. Why torture him with the fleeting life and painful death of his soulmate if they were never even fated to meet in the first place?
A tug on his Thread cuts all of his stray thoughts loose. He strains his eyes wide open, ready to witness. This is it, then. The end.
But the Thread doesn’t fall away. Instead, it snarls, tangled up in something heavy and alien and wrong, and wraps itself tightly around Yuuta’s pinky again.
Which must mean... somehow, after hours shrouded in the veil of death, his soulmate is now alive.
A few weeks later, Gojo-sensei comes to visit with ominous words on his tongue. He asks Yuuta to take special care of a new first year student, Itadori Yuuji, a boy who’s lived and died and lived again.
And Yuuta wonders.
He finds Itadori Yuuji in a curse-infested Tokyo, in the early November cold amidst two strangers. The unexpected company complicates matters, dashing his hopes of guiding Itadori through a gentler death and rebirth the second time around.
His pinky pulses with a phantom heat. Is it really him, or is it just Yuuta’s wishful thinking? He’s too far away to check; Thread connections might be visible to those who can see curses, but only when soulmates are no further than one or two meters from each other.
It doesn’t matter either way. In order to fulfill his binding vow and keep Itadori safe a little while longer, Yuuta must play his part correctly now.
He tasks this Zen’in Naoya guy with distracting the other one and leaves them both behind in pursuit of Itadori. He’s faster than Yuuta had expected, fleeing down the street in a burst of speed, but the distance between them narrows all the same.
Just a little closer...
When it happens, the bright burst of cursed energy is so intense it leaves Yuuta with no doubts. Red shimmers to life in a delicate arc connecting their hands, a thin line of fate flickering in and out of existence as they run right at the edge of the visibility distance.
Yuuta’s mask slips. He can’t help but grin, giddy at the confirmation.
Itadori—or, if Yuuta may be so bold, Yuuji—has a very expressive face, he notes, and right now it’s slack-jawed with shock, boyishly youthful under his harsh, fresh-looking scars.
“You’re—?!”
“I am,” Yuuta agrees. “Hi, soulmate.”
They’re both distracted in the fight that ensues. Yuuji’s confusion makes him pull his punches, uncertain. Yuuta, on the other hand, keeps glancing down at their shared Thread and feeling butterflies explode in his chest. His mind teases him with visions of Yuuji wrapped in red silk rope, safe from harm, all his.
The excitement makes him press harder, strike faster. And, to his credit, Yuuji regains focus quickly. He’s strong like Maki, and he’s resourceful, too, somehow managing to scavenge up a knife from an abandoned car.
He pushes forward, and their blades clash and lock, metal screeching as sparks scatter into the air. Yuuta’s attention drops to their hands again, to that vibrant red line connecting them, the shortest he’s seen yet. But Yuuji...
“You’re too focused on my katana,” Yuuta says, disappointed. He sends him flying back with a foot planted on his chest and gestures towards his own pinky. “Aren’t you interested in the Thread at all?”
Yuuji shoots him a look of pure incredulity, arms braced in front of his chest in defense. “Does being interested in the Thread mean you’ll stop trying to kill me?”
Well. “No.”
“Then no, I’m not really interested right now. Sorry.” His face hardens into something resolute, serious. “But I can’t die just yet.”
It’s surprisingly relieving to hear. Yuuta knows all too well the sickening taste of guilt rising from his stomach, the heavy burden of power too strong to bear. If Yuuji still has something to live for after what had happened at Shibuya, then Yuuta wants to help him any way he can.
There’s just one problem.
“You can die,” he corrects, “and you will.”
The next swing of his sword cleaves Yuuji’s knife into pieces, but his advantage doesn’t last long. In the same movement, the tip of his katana is forced into the ground under Yuuji’s foot, and a following stomp snaps his blade clean in half. Given how much cursed energy he’d been channeling into the thing, Yuuta’s honestly impressed.
He didn’t think this would be easy, but he also hadn’t anticipated how much fun he’s having.
“What’s going on here?”
As if summoned by his joy, Rika-chan appears, manifesting behind Yuuji and drawing him into a sulky, clingy hold.
Yuuta tries his best not to react, knowing better than to encourage her jealousy. “We’re just playing,” he tells her. And then, so she doesn’t feel left out: “Hold him for me?”
He can see the rising panic in Yuuji’s face as he fails to struggle out of her arms. Their Thread shrinks in length with every step he takes, swaying with the movement, until Yuuta reaches him and weaves their fingers together.
Yuuji squeezes back, hard.
“Oh, wow, you’re strong!” Without cursed energy, he would’ve shattered every bone in Yuuta’s hand for sure. As it is, the ache in his joints is comforting, grounding. Real. “You can relax, though. This is for your own good.”
“What, dying?”
Yuuta dodges a half-hearted kick and looks up with a helpless smile. “That’s right,” he says. “I think you might already know, but I hear being dead is a pretty good camouflage.”
The words seem to sink in slowly. “... Camouflage?” Yuuji echoes, after a beat.
Yuuta nods once and readies his broken katana. “I’ll give you the details later, but we don’t have much time.” He still has to sort out the other two people, after all. “Just trust me. And... sorry if this hurts.”
He averts his eyes from the blade piercing Yuuji’s heart with a wince and examines their Thread instead. The tangled mess around his pinky starts to fray again, weakening exactly in the same way as it had months before.
Now that he isn’t distracted by the threat of imminent injury, Yuuta can tell their Thread is soaked in malevolent cursed energy, clinging where it doesn’t belong. It’s Ryomen Sukuna’s, most likely, a binding vow Gojo-sensei admitted to suspecting the existence of when he’d pressed the man for details in the summer.
Yuuta hates it. This is his Thread, his soulmate, his life to learn to love. Yuuta will be the one to tether Itadori Yuuji to the land of the living, and as he begins to use his reverse cursed technique on Yuuji’s physical body, he focuses on excising that unnatural cursed energy from their Thread as well. He reinforces their bond instead with his promise to keep Yuuji safe, his devotion to support him both now and in the distant future, his desire to love.
The Thread reforms slowly, no longer twisted knots or a simple child’s bow but something braided and interwoven and beautiful.
A weight lifts from Yuuta’s shoulders. He presses a kiss to the base of Yuuji’s pinky, under their Thread, relieved.
There are still far too many things left to do, but for now, all that matters is his soulmate lives.