Work Text:
When Sukuna wakes up, he doesn’t know where he is. The light is dim, barely enough to illuminate the inked seals plastered floor-to-ceiling on the walls. No door. A containment room of some kind, then, meaning that whoever put him here doesn’t think they can take him on without extra help.
And yet, curiously, he himself is unbound. His wrists are bare, his ankles unchained; the only difference he notices is a thin black line, a dainty addition to the tattooed bands he already displays proudly. He brings a nail up, scratching at it, but the ink doesn’t chip or flake. Interesting.
“Ah, you’re up,” a voice says from behind, and Sukuna whirls around to see a man with long black hair, dressed in monks’ robes and smiling placidly. There is no sign of a door or opening behind him, as if he had simply appeared from thin air. “I had wondered how long you would be out.”
“Who are you?” Sukuna spits.
The man tuts. “You don’t recognize me? I suppose it has been a while…” He steps forward, and the candles in the corners flicker with the movement. “...Sukkun.”
Sukuna swallows. Only one person has ever dared to call him that. “Kenjaku,” he says, forcing his voice to stay calm even as his heartbeat skyrockets. “Don’t call me that.”
Kenjaku smiles and steps even closer, and this time Sukuna can see the stitches bisecting the forehead of their latest victim, the lines smooth and steady as ever. “I was worried you had forgotten me,” they say mildly.
“How could I,” says Sukuna. He glances back at the corners of the room—even those are covered in seals—and lets his eyes rove over the walls for any trace of an exit, a door or a window or even a weak spot he could slice through.
“It’s been a long time,” Kenjaku says, coming closer still. Against his will, Sukuna takes a step backwards, and then another, until his back hits the wall, and still Kenjaku presses closer, caging him in. “I missed you, you know.”
“I didn’t miss you,” Sukuna spits. “What do you want? Why am I here?”
Kenjaku sighs, tucking a strand of hair behind their ear. “So ungrateful! I helped you out, didn’t I? We spent a very long time working on your seals. It’s not easy to control that much cursed energy.”
“You stole my power!”
“And then I returned it, hm?” Kenjaku tilts their head. “Your cursed energy was necessary in order for me to produce a vessel for you. One specifically tailored to harbor the great Sukuna-sama in mind, body, and soul. And I did a good job, didn’t I?”
Sukuna grits his teeth at the mocking tone. “You twisted the terms of our vow.”
“Like you haven’t?” Kenjaku smirks. “Pot, kettle.” They rock back on their heels, and let their gaze trail down Sukuna’s body. Sukuna is suddenly acutely aware of the clothes he woke up in—or rather, the lack of them, exposing him to open air from head to toe. “And it was worth it, wasn’t it? My son’s body is quite lovely.”
“Wh—who—your son ?” Sukuna, as a rule, does not splutter. Kenjaku has a way of coaxing out every reaction he tries to tamp down. It’s part of why he hates the other curse so much. In front of them, every drop of fear, every bit of anger, of pain—it’s all laid bare. There are no secrets before Kenjaku’s calculating gaze.
They grab Sukuna’s outstretched wrist and guide it to the flat plane of their stomach, pressing into the spot where a womb would be. “Doesn’t this feel familiar? You spent so long inside me, after all.” Kenjaku’s grin widens, haunting, a row of gleaming ivory that threatens to split their face in two. “Do you know what it takes to ensure that a cursed vessel will retain its original form and sentience?” They don’t wait for an answer. “It’s hard enough to produce a vessel that will survive in the first place, after all. I had to track the Itadori bloodline for centuries. They have a natural resistance to cursed energy that makes them quite suited for this purpose. And, did you know? Their ancestors are from Hida-no-kuni. Just like you, Sukkun.”
Sukuna swallows. “What—”
“In order to survive, a cursed vessel must be continually exposed to cursed energy while still in utero,” Kenjaku continues. “The closer the cursed energy signature is to that of the incarnated object, the better the results.” They smile, again, and stroke over their stomach, cradling an infant long gone.
“You seduced your way into the brat’s family just to baby-trap them? That’s low, even for you, Kenjaku,” Sukuna spits.
“‘Baby-trap?’ What sort of language has my son been teaching you?” Kenjaku furrows their brow. “No, no, nothing like that. I did it as a favor to you, to fulfill the terms of our vow. Without my own cursed energy, your vessel would have burnt itself up as soon as it swallowed one of your cursed objects….Of course, that is always a risk with these sorts of experiments. But it worked! It worked even better than I expected. And now…”
Kenjaku’s voice dips. “Now, I take back what’s rightfully mine.” They reach out, slowly, and place a hand on Sukuna’s chest. “Turn around, please.”
Sukuna snarls and bats the hand away. “Don’t fucking touch me.”
“Don’t talk back,” Kenjaku says mildly. “You agreed to this, remember? It’s in the terms of our vow."
“I never agreed to anything,” Sukuna spits, and summons his cursed energy, slashing downwards. He’ll cleave this slimy bitch in two, and then he’ll cleave his way out of this room, and then he’ll slaughter whatever other sad fucks Kenjaku has manipulated into doing his bidding, and bask in their blood—
Nothing happens. Sukuna freezes, his arm outstretched, black nails pointed towards the ground. He can feel his cursed energy, bubbling under his skin, but it’s formless and unresponsive. The usual easy pull into a cursed technique is gone.
Kenjaku tsks. “Really, Sukkun, did you think I spent those thousand years sitting around and waiting for you? I set the whole thing up! You wouldn’t have been sealed without me, and you certainly wouldn’t have been reincarnated without me.”
Fuck. The new lines on his skin must be an extension of Kenjaku’s sealing technique, blood and cursed energy bound together and tattooed into his core. A shackle at the molecular level.
“You fucking bastard,” Sukuna spits, rage boiling up inside him, “I’ll fucking kill you—” He lunges forward, intent on burying his fist into Kenjaku’s smug face, cracking their skull and clawing that parasitic mess of gray matter out with his bare hands. Kenjaku smoothly parries the motion, kicking his ankles out from under him and spinning him until Sukuna is cornered, back pressed flat against the wall, Kenjaku pinning his wrist over his head. Their other hand grips his forearm tight enough to bruise.
“Don’t pick a fight you can’t win,” Kenjaku says. “Your cursed energy is sealed. Mine is not. If you’d like that to change, you’ll be good for me.”
There’s a sick feeling in the pit of Sukuna’s stomach as Kenjaku guides his other hand above his head, adjusting their grip until both of his wrists are pinned in place. “Good boy,” they croon, and it slips heavy and nauseating inside him. “Just like that.” Their hand skims over his chest again, tracing over the tattoos on his pecs, then his ribs, following them downwards until their hand brushes against his pubic hair.
Sukuna grunts when their fingers—still long, still slender—wrap around his soft cock. Kenjaku flicks their wrist deftly and sets a steady pace, a slow and constant stimulation that has him reacting against his wishes.
“See?” they ask, rubbing their thumb over his slit. “You’re hard already. It’s been a while, hm, Sukkun?”
Sukuna bares his teeth. “There’s not a lot of opportunity to fuck when you’re chopped up and sealed.”
Kenjaku squeezes the base of his cock. “You’re right, I’m sorry. It must not have been very fun, trapped for all those years….” The hand pinning Sukuna’s wrists twitches, and something winds around his wrists, thin and warm with a rubbery texture that digs itself into the wall. He tugs at it, but it doesn’t budge. If he wasn’t trapped in this shitty, dark room before, he is now.
They drop to their knees, heedless of the billowing robes their host body is wearing, and smile beatifically up at Sukuna. “Let me make it up to you.”
“Wait, don’t…” Sukuna starts. Dread is bubbling in the pit of his stomach.
They pause with their mouth open, their tongue a scant few inches away from the head of his cock. “Don’t? You don’t want me to make you feel good?”
Sukuna grimaces. “I’d rather you just—just get this over with.”
Kenjaku’s smile grows even wider. They grin up at him with cat-slit eyes, pumping his cock to keep him hard. “Oh, but I want to take my time.”
“It’s not necessary,” Sukuna grits out, “Just—”
He exhales roughly as Kenjaku wraps their mouth around the head of his cock. Their tongue is slick and wet, their mouth warm around him, a solid, spongy pressure that curls and snakes around him. It should feel good—fuck knows Sukuna loves getting head—but the signal is all wrong, the neurons firing incorrectly. Instead of the usual toe-curling pleasure that the tight, wet heat of a willing mouth gives, it just feels alien and disgusting.
Sukuna lets his head thunk back against the wall, keeping his eyes trained on the ceiling. He can’t bring himself to look down, can’t force himself to look at Kenjaku’s lips wrapped around his cock, but the lack of visuals only heightens the sensation: wet in a bad way, foreign and unpleasant. His stomach churns.
Kenjaku swirls their tongue over his slit before pulling off and kissing down the underside of his cock. They roll his balls gently in their other hand, tongue darting out to lick over the sensitive skin, and Sukuna exhales shakily.
A thousand years and a dozen bodies ago, Kenjaku would lay him out on silks and furs, spent hours laving their tongue over every inch of his body, bringing him to peak again and again. Back when they still danced around each other, a choreographed give and take of sex and power. But Kenjaku’s machinations ran even deeper than Sukuna could have anticipated, and the give and take dwindled until only the take remained.
It used to make him feel powerful, to have them on their knees in front of him. Now it just makes him want to puke.
Kenjaku’s fingers skirt lower, rubbing over his perineum. At the same time, they lick a hot stripe back up his cock, pausing until air cools the trail of saliva before plunging back down.
Sukuna makes a strangled noise at the dual sensation of fingers against his taint and the hot, wet pressure of Kenjaku’s mouth.
Kenjaku hums, pleased with themselves, and their fingers press in tighter for a single instant before darting away. When they return, they’re slick and wet, and slip easily between his cheeks, smearing lubricant over the skin.
It’s impossible for Sukuna to hold back his groan at the sensation of his hole being breached. Kenjaku aims immediately and unerringly for his prostate, and the slick heat of him is almost enough to distract from the burn. If he moves his hips forward to get away from the fingers inside of him, he’ll press his dick deeper into the recesses of Kenjaku’s throat, but if he arches back to get away from their mouth, he’ll fuck himself further onto their hand.
Kenjaku swallows around him, and Sukuna bites the inside of his cheek to keep from moaning. It still feels wrong, Kenjaku’s mouth and hands on him an unwelcome intrusion, but the other curse knows his body well. His fingers reach deftly inside him and pluck out reactions like coaxing a melody out of a harp.
The fingers inside him thicken and writhe, and Sukuna keens at the sensation. It’s barely been any time at all, there can’t be more than one or two inside him, and yet he feels stuffed full. Kenjaku’s fingers stretch him even further open, a constant blunt pressure on his prostate, curling up deep inside him—
Sukuna’s eyes fly open. He jerks his gaze down to Kenjaku, still smirking up at him even with his cock down their throat, one hand wrapped around the base of his cock and the other disappearing between his legs. Their stitches seem to waver, a hallucinogenic pulse that stretches them up, up, up, constantly lengthening but still remaining the same size.
“What the hell is that,” Sukuna breathes.
Kenjaku pulls off and quirks an eyebrow at him. “Is something the matter?”
“What the hell is inside of me!” Sukuna snaps. He can feel the panic building up inside him, his lungs pulling tight, the oxygen in the room thinning. “Get it out!"
“I apologize,” Kenjaku says, looking rather smug about it. “I had assumed that you didn’t want me to take you dry—”
“Get it out!” Sukuna cries, his voice cracking embarrassingly high as the thing inside him pulses. “Get it out get it out get it out!”
“Say please,” Kenjaku says, gazing up at him adoringly, licking their lips like his panic is the best thing they’ve ever tasted.
“Fuck you,” Sukuna spits automatically. The thing moves, sliding against his insides, and Sukuna arches his back in a futile attempt to get away. “Fuck! I’m sorry! P-please! Please take it out….”
“Say you want me instead,” Kenjaku says. “Say you want my cock. Beg for it.”
Sukuna can feel the palm of their hand pressed up against his ass, forcing the thing to stay inside him, and he’s struck with the sudden image of it crawling up further inside him, tunneling through his intestines, burrowing deep through organs and flesh—
“Please,” he sobs, “please, I want you instead, I want you inside me, I want your cock, anything but this, take it out, take it out, please, please, please—”
Kenjaku’s face softens. “Oh, good boy,” they croon. “It’s been so long since I’ve heard your lovely voice crying for me.”
Their hand lowers, and the thing slides out of him, inch by awful inch. Sukuna sobs at the relief, letting his body sag against the bonds still keeping his wrists tied over his head. When it finally drips out of him, leaving him blessedly empty, Kenjaku shifts back onto their haunches.
They hold up their hand, and a grub-like curse curls around it, fat and plump. Its sickly yellow skin is ribbed and glistening in the dim light. On its head is a single, blood-red eye, curved around the arc of its skull. A drop of sticky fluid trickles off of it and down Kenjaku’s arm. The curse curls up on itself, wrapping tail over body until it’s no bigger than an orange, resting in the palm of Kenjaku’s hand.
Sukuna stares in horror as Kenjaku tilts their head back and places the curse in their mouth. They swallow it down easily, smoothly, the only remnant of its existence the thin sheen of lubricant that gleams on their fingers.
“This body has a very interesting cursed technique,” they say as they stand, shucking off their loose clothes. Their insect-sticky hand grips Sukuna firmly by the hip. “Cursed Spirit Manipulation. I’ve never seen anything quite like it.”
They guide Sukuna’s legs up to wrap around their waist. It pulls at his wrists uncomfortably, but he doesn’t say anything. His mind is awhirl with the implications—cursed spirit manipulation? It fits Kenjaku almost too well. He imagines curses coiled up and swallowed down, nestled in their stomach like eggs, their belly fat with them, swollen as if still carrying the child whose body Sukuna now occupied—
Kenjaku presses their length inside him, their hardness a stark contrast to the writhing malleability of the grublike curse they’d stretched him open with. They groan as they sheath themselves fully, fingers flexing where they hold Sukuna aloft, and then they begin to fuck him.
This, at least, hasn’t changed. Kenjaku’s cock is different from the one they had a thousand years ago, but they fuck him just as fast, just as unrelenting. They fuck him with single-minded intensity, and with his cursed energy sealed and his hands bound, all Sukuna can do is take it. Every thrust slams him against the wall, pressing his back into the seals plastered there. The ink of the characters burns where it touches his skin, his blood brought to the surface as if magnetized. When he pulls away, will the seals be branded into his skin?
Kenjaku’s cock scrapes against his insides, branding him there as well. The lube in his ass is already drying out, turning the space between his legs tacky and sticky. Even as the stretch becomes painful, he’s pathetically grateful that they removed the curse they used to open him up.
Sukuna stares unseeingly at the far wall, the seals sinking and swelling before his unfocused gaze. It’s bearable like this. It’s less personal than their mouth on him, wet and horrible, their tongue an alien twist of muscle slurping messily at his cock. No maggots feasting on him from the inside out, this way.
“Suk-kun,” Kenjaku murmurs, the corpse of the second syllable dragging behind its twin. “won’t you look at me?”
Sukuna’s traitorous eyes tilt down until his gaze meets Kenjaku’s. They smile, unperturbed as always, the corners of their eyes crinkling into perfect crescent moons. “Good boy,” they croon.
“Don’t call me that,” Sukuna says. The protest sounds weak even to him.
Kenjaku purses their lips in a fake pout, but their hips keep pistoning into him. “Such a cute nickname, though,” they say. “A cute nickname for a cute little boy.”
“Fuck off with that shit,” Sukuna snarls. He hates the way his face flushes when they speak to him with that patronizing lilt in their voice. “I’m 1500 years old and your cock is in my ass—”
“1500 years and yet you still can’t control your language?” Kenjaku smirks. “What are we going to do about that?” They hoist Sukuna higher up, changing the angle of their thrusts, and hit his prostate dead-on.
Sukuna goes boneless, unable to stop the breathy gasps that escape his lungs every time Kenjaku fucks into him. It’s good, he hates how it’s still good, even after they betrayed his trust, even after they manipulated him into giving up his power. Thousands of years spent crumbling into dust—bound and declawed—plans laid to ruin, power left to rot—none of it matters when they still fuck him so perfectly.
“I’m the only one who can make you feel like this,” Kenjaku hisses, and Sukuna, despite himself, agrees. When Kenjaku comes, Sukuna can feel it deep inside of him, blood-hot and slick like the grub-curse from before. Hideous, writhing, alive; painting him from the inside out.
Kenjaku shifts Sukuna’s weight to one hand and jerks him off rhythmically, methodically. He comes weakly, drops of white barely dribbling over his tip, coating Kenjaku’s long fingers.
Their cock slips out of him. Liquid trails down his thighs. Sukuna groans at the sensation, raw and open and used. Vaguely, he’s aware of the rope keeping his wrists bound becoming undone, and he lets his arms drop down, resting them on Kenjaku’s shoulders. His weight is fully supported by the other curse, now; a mockery of a lovers’ embrace.
“Thank you, Sukkun,” Kenjaku murmurs, and leans in to kiss him. Their tongue slips in between his lips, shockingly cool and longer than a human’s should be. Their mouth tastes like bile and some distant sense-memory of rot, like the grub curse was still clinging to their throat, its sticky fluid replacing their salivary glands.
Sukuna gags at the taste, pushing weakly at Kenjaku’s shoulders. Unexpectedly, they let him push them away, gently lowering them until his wobbly feet hit the ground. Sukuna sinks to the ground, thighs shaking, cum and curse-lube dribbling out of him onto the floor. The seals against the wall still burn his back, but the sensation hardly registers. He works his jaw, slowly, then spits onto the ground, as if that would ever get the taste of Kenjaku out of his mouth. “I’m going to kill you,” he growls, glaring up at them.
Kenjaku smiles, reaching down to pull their robes back on. “I could use the entertainment,” they say. “Do give a shout when you can stand.”
Sukuna hadn’t noticed until now, but his legs are still trembling, his muscles screaming in protest as if he was the one who’d held someone up against a wall and fucked them. His body feels odd, frail, weak. “What the hell did you do to me?”
“I just needed to be sure you still broke the same,” Kenjaku says. They calmly tie the sash around their waist. “Oh, by the way, when my son comes out, do tell him I said hello.” They brush a stray strand of hair out of their face. “Or was he already awake, watching you take cock like a professional whore?”
“You stay the hell away from Yuuji, you sick freak,” Sukuna spits.
Kenjaku quirks an eyebrow. “First-name basis already? Do I need to defend his honor?”
“He’s my vessel,” Sukuna says. “Mine to ruin—mine to own—”
Kenjaku squats down at eye level with Sukuna. They pat his cheek condescendingly, getting in close even as Sukuna snarls, fingers twitching with remembered power. “I made you, Sukuna. The both of you. I will do what I want to you.”
They rise smoothly and brush imaginary dust off their legs. “Remember that, and be good, now. I’ll be back soon.”
The door swings shut, and the dim light fades to blackness. Sukuna is alone.