Chapter Text
Yuuji snuggled into Megumi's back, halfway to a doze.
“Brat, I'm bored of this. You've been snuggling like a fucking sap for ages. Get up and do something already.”
Yuuji sighed heavily and buried his face in his boyfriend's neck. Of course. Even though Sukuna enjoyed sharing body warmth, he hated sitting still for too long.
“What's wrong?” Megumi turned a page of his book idly.
“Sukuna’s bored.” Yuuji groaned. “I don't suppose you'd be up for some sparring, maybe?” That usually cheered Sukuna up real fast. Whether because of the violence or because of him roasting Yuuji’s combat skills.
“Meh.” Megumi didn't look up from his book. Yuuji slumped against him.
“What if I want a different kind of action?” Sukuna’s mouth formed on Yuuji’s neck at an odd angle. Yuuji jumped at the phantom sensation of taste as Sukuna decided to lick the back of Megumi's neck.
Megumi leaned away from them with a grunt. “Not in the mood.” That was pretty typical honestly. They hadn't been dating for very long, almost two months now, but Megumi wasn't nearly as sex driven as Yuuji was. That wasn't even mentioning how high Sukuna’s was.
Yuuji sighed as he shoved Sukuna down before he could cuss Megumi out. “That's fair. Sorry, I'll keep him from being gross.”
“Fucking little shit should be HONORED to receive an offer from me!”
Ironically despite not hearing him Megumi spoke. “No offense, Sukuna.” Megumi actually looked up to give them a shrug. “I'm just… tired.” That… made sense. He'd been pretty down lately. Really quiet, even by Megumi's standards. Something about the Zenin clan bothering him? It meant that Yuuji and Nobara were sort of coddling him a lot, the past week.
“It's okay.” Yuuji snuggled back into Megumi's shoulder, pulling his phone out to text with one hand. “I'll see when Nobara's getting back from her grade exam! She'll probably be down to celebrate, right?”
Megumi relaxed back into him as well, enjoying the physical closeness.
deadlast: HEYYYY <3
deadlast: hows the mission going bb?
finalgirl: yuu I am going to commit an atrocity
Sukuna perked up.
deadlast: PLS dont say that when sukuna is boredddd DX
finalgirl: if I wasn't so determined to get this grade promotion by my own gaslight gatekeep girlboss power I might use the fact I've sucked The sukuna’s dick to scare this asshole into not being such a pussy
deadlast: ???
finalgirl: he is taking his SWEET ASS TIME confirming ANYTHING I want to do on this case bcz he is SOOOOO cautious I am losing my MIND
deadlast: awwwwww
finalgirl: anyways yeah so I'm not gonna b home anytime soon
finalgirl: sry I kno he gets horny when he's bored
finalgirl: if u 2 are patient we can have fun when I get back but idk when that'll be
deadlast: its ok!!! Ill figure smth out
Yuuji sighed and closed his eyes, trying to ignore Sukuna’s grumbling and cursing. He went back to nearly dozing against Megumi's back for a few minutes.
“Brat. I've got an idea. Brat, go take a fucking nap.” Sukuna snapped.
“Why do you want me to take a nap?” Yuuji opened his eyes, immediately suspicious.
Megumi, used to him having one-sided conversations with Sukuna, just raised an eyebrow.
“Because our domain can be used for a lot more than just fighting and killing you.” He sniffed.
“...I think Sukuna wants to have domain sex. Is domain sex a thing?”
Megumi lowered his book to Look at him. “...maybe? Not many sorcerers can actually make domains so I'm not sure. Are you talking about a domain expansion? Or just your shared innate domain?”
“I mean, both could work, if he wants to join~”
“Megumi's not in the mood.” Yuuji scolded, seriously shoving at Sukuna’s presence. “And apparently both are possible?”
“...huh.” Megumi made a face. “Still not in the mood. And sorry, but I'm going to have to refuse domain sex on principle until I have a foolproof vow figured out. It's already risky enough when he participates with your body. Giving Sukuna free reign outright? No thanks.” He shook his head as he returned to his book.
Yuuji snickered at the mixed feelings coming from Sukuna. On one hand, he despised being turned down. On the other, he approved of Megumi's intelligence and due caution when interacting with the King of Curses. That showed ‘respect’ or something like that.
“Idiot. Just go to sleep and I'll pull you into my domain.” Sukuna growled.
“Well what if I'm not in the mood?” Yuuji pouted. Mostly just in protest of how pushy he was being.
“Brat, I will rip your HEAD off tendon by tendon next time you fall asleep if you don't get your dumbass in here right the fuck now-”
“Yeesh, calm down, drama queen.” Yuuji groaned and flopped backwards onto the bed. “Standard deal about hurting me?”
“Only in ways we both wish, for the duration of the encounter.” Sukuna responded, smug that he'd finally got Yuuji into the habit of using the myriad of vows that balanced their weird relationship.
The vow locked into place and he felt a shiver go up his spine.
“Guess I'm having nap sex now, I guess?” Yuuji said, bemused.
“You said guess twice.” Megumi's lips twitched faintly. He rearranged himself to sit up by the headboard. “Just don't make too many weird noises in your sleep. This is still my bed.”
“And you have the comfiest bed!” Yuuji grinned up at him.
Megumi reached down to pet his hair a few times before going back to his book.
Yuuji blinked his eyes open sometime later to the red atmosphere of Sukuna’s domain. He sighed and sat up, unsurprised to find himself laid out in a pool of blood. He tried to brush the liquid out of his hair.
“Man it's weird that I'm just used to being soaked in blood.” Yuuji thought out loud. It bothered him still, but mostly just because of how weird it felt when it dried.
“Why? You look rather handsome drenched in crimson.” A hand rested on his head and pulled him to his feet by the hair. Yuuji hissed in annoyance.
“Because it's gross?” Yuuji rolled his eyes, trying to pull away. He frowned at Sukuna and the dirty expression on his mirrored face. “Dude, I… dunno if I can fuck myself.”
Sukuna’s eyes narrowed unhappily. “Truly? That is where you draw the line?” At least he was as amused as he was annoyed.
“It's weird!” Yuuji raised his hands as he successfully pulled away without losing chunks of hair. “When we do stuff normally it's just- sharing my body, I don't actually look at you looking like me.” Honestly Yuuji never much liked Sukuna using his face, but the curse liked fucking with him too much to use his real form most of the time.
Sukuna stared at him for a minute, mouth pressed in a thin line. Then he stalked forward and towered over Yuuji, growing and shifting as he turned into his true curse form. Yuuji took a step back- but not fast enough.
Large arms swept him into Sukuna’s grasp, spreading his legs and propping him against his abdomen like he was a child.
Sukuns smirked, fangs bared. “Well? Is this better, brat?”
Yuuji was a little breathless. Sukuna preferred to use his own body and face just to freak Yuuji out. But he did use his natural state every now and then, in their domain. Usually on those occasions Yuuji spent the entire time running and fighting for his fucking life. He didn't really get the chance to look at Sukuna.
Maybe it was the leer on his face. Maybe it was the way one of his hands was big enough to cup Yuuji’s entire ass. Maybe it was the shifting directly against Yuuji’s crotch. But Sukuna’s true form was suddenly… a lot hotter than he'd thought it was.
Sukuna chuckled, sensing the direction of his thoughts. “Plenty of mortals have screamed my name in pleasure as well as fear, Yuuji~” He leaned down to press a weirdly chaste kiss to Yuuji’s forehead. Then he ruined it by licking a long stripe across the side of Yuuji's jaw.
Yuuji shivered and wiggled, trying to pull back. Sukuna put one hand behind his head to stop him.
“Don't run from me, Yuuji~” Sukuna growled, vibrating Yuuji’s entire body where it pressed up against his giant chest.
“Sukuna…” He squirmed, already feeling like this might have been either a really good idea or a very bad one.
“Don't worry, you already know you can't die here.” Sukuna grinned, mouthing at Yuuji’s neck. He moved downwards and nipped at the collar of his T-shirt, tearing it between his teeth.
Yuuji was a little distracted by the movement beneath his spread legs. “Dude..!” He squirmed. “You're so lucky that shirt isn't real-” What was up with Sukuna ripping his shirts off?
One hand kept Yuuji’s ass in one spot, another kept his head from moving, and the other two were dedicated to removing their clothes. Sukuna’s yukata was pulled down and Yuuji got to see the large mouth on Sukuna’s abdomen that immediately began to mouth at his jeans.
“Oh holy shit-” Yuuji wasn't expecting that to be as hot as it was. He was a little scared, what kind of person wouldn't be terrified of a giant mouth scraping its fangs around their junk? But reminding himself that this was Sukuna and Sukuna couldn't actually hurt him (right now (too much)) helped make his shivers a little less terrified.
Sukuna’s yukata was in shreds, Yuuji’s jeans and boxers following not too long after. Sukuna pulled him away just long enough to pull their pieces out from between them. Then he slid Yuuji right back up against his body, heat radiating between them.
That mouth immediately latched onto Yuuji’s entire crotch, giant tongue cupping his groin and licking. Yuuji gave a startled yell that quickly turned into a moan.
He rested his head on Sukuna’s pec, breathing heavily. The hot moist environment covering his entire crotch holy shit was mind blowing. The tongue immediately wriggled and sucked on him and he whined shrilly.
“H-holy shit, Sukuna, t-too much-!”
“I don't really control that mouth.” Sukuna chuckled deeply. “It mostly does what it wants.”
“A-and it wants to suck my entire ass?!” Yuuji arched his back, body unsure whether to pull away from the overwhelming sensation or rut into it. “Hhh- fffuck! Dude!”
Sukuna laughed, chest rumbling. He pulled Yuuji in for a deep kiss. The size difference was intense. Sukuna dominated his entire face and mouth with an intensity he didn't know how to respond to. He'd never kissed somebody quite like this before. Sukuna’s tongue almost choked him as it forced its way to the back of his mouth.
The tongue underneath him was moving nonstop, licking and sucking on him. He could feel drool dripping down his thighs. Yuuji was starting to get used to it, rocking back and forth with a soft moan.
Sukuna drew back from their kiss, looking smugly down at him. He pulled Yuuji’s head back by the hair until his neck was arched, whining helplessly.
The tongue underneath him slipped and forced its way between his cheeks. Yuuji yelped and squirmed as the tip prodded at his ass.
Sukuna just laughed, walking them somewhere and wading through blood nonchalantly.
He was tossed down on a soft surface. Cold hit his junk as he was detached from the hot mouth. Yuuji blinked dazedly to find himself inside of Sukuna’s shrine, laid on a soft bed covered in blankets and pillows. Say what you would about Sukuna, but he wasn't the sort to skimp on comfort.
“Yuuji…” Sukuna crowded over him, making him feel absolutely tiny as he began to nip and mouth at Yuuji’s neck.
Yuuji tilted his head back, sighing and groaning. An idea was forming from Sukuna. An idea that had Yuuji's dick twitching. The mental image of Yuuji riding on Sukuna’s tongue like a saddle, the giant one from his second mouth, kept flickering behind his eyes. He almost choked on his spit when it changed to him riding Sukuna’s dick.
“Holy shit.” He breathed, having to blink a few times. Finally, Yuuji took a look down at what Sukuna was packing.
Sukuna was big in general. Not only was he eight feet fucking tall, but he was wide. Thick and muscular enough that he'd dwarf anyone even if he was more of a normal height. It always meant that Yuuji knew, proportionally, that Sukuna would have a big fucking dick.
His dick was long as and big around as Yuuji’s entire forearm. And Yuuji was proud of how thick and muscular his arms were. Sukuna’s dick was the same fucking size.
“Oh holy fucking shit.” Yuuji breathed. “Sukuna there is no fucking way that's gonna fit up my ass.” The most he'd had inside of him was Megumi or a freaky toy Kugisaki liked using. And that had taken some stretching first.
“It's fit inside plenty of humans before. And this is my domain; the body isn't as firmly entrenched in reality, here, brat.” Sukuna huffed. The mouth on his abdomen drooled, tongue dripping over Yuuji’s crotch and slobbering up his abs. “And for that matter, while women might struggle to fit me, men certainly have an easier time of it.” He sniffed haughtily. Of course, Sukuna probably would love to literally kill Yuuji on his dick, but that went against their rules, even if he wouldn't actually die since this was a domain.
Yuuji ran the logic through his mind a few times. Yeah, that seemed like it made sense. Probably?
“Of course it makes sense, idiot.” Sukuna pressed his fangs into his shoulder and Yuuji gasped. He cried out in a bit of surprise as pain shot through him, mixing with pleasure because Sukuna had gotten him thinking biting until he was bloody was hot. “I'm hardly new at this.” The curse drew back just enough to speak and lick the bite mark, digging his tongue into the holes. “Learn to trust my knowledge a little more, brat.”
“I-I don't know.” Yuuji kept looking Down. Sukuna’s dick was hard and pressed into his legs, rutting idly. “That's still like- pornstar levels of big. Are you sure it won't hurt?”
“Of course it's going to hurt, you buffoon.” Sukuna growled. “That's half the point. If I don't have you screaming by the end of this what is the fucking point?” Another bite, another gasp from Yuuji.
“It doesn't have to hurt you damn sado.” Yuuji pouted a bit.
“If I'm a sadist, you are a masochist.” The curse chuckled. Hovered over him like he was, the very air felt like it shook.
“We're both masochists.” Yuuji grumbled reluctantly. “Okay, just- hey!” The moment he spoke Sukuna had grabbed him and sat up, holding him in two hands like a puppy. “Let me finish asshole!”
“I'll make you finish alright…”
“Dude!” Yuuji kicked at him, only for his entire foot to go into the lower mouth. Yuuji’s mouth went dry as it suckled on his lower leg like something obscene. “Oh ffffuck that shouldn't be hot, I don't even have a foot fetish.”
Sukuna laughed maliciously, leaning back against his mountains of cushions. He had to pull Yuuji away from the lower mouth like taking a toy away, physically tearing his leg from the tongue's grasp. Then he settled Yuuji right on top of the mouth and it reattached itself to his crotch.
Yuuji couldn't even hope to stop the loud cry that came out of him when that wet heat wrapped around his cock and balls. It massaged him all over, tongue writhing excitedly.
“Don't worry, I'll behave.” Sukuna probably rolled his eyes. Yuuji wouldn't know, he was too busy seeing stars, but he could tell by his tone that Sukuna was probably rolling his eyes. “I'll just get you nice and pliant before fucking you. That always works.” One of his giant hands traced down Yuuji’s spine and he shivered. Just one of Sukuna’s fingers was as big as Megumi's dick. The fingers sure shrank down when they became all mummified and gross in real life.
Claws dipped to his lower back and traced between the top of his ass cheeks… then scratched up across his back. Yuuji yelled, arching and trying to get away instinctively. That wasn't a cute little catscratch like Nobara liked doing. That was deep. Deep enough that Yuuji felt blood immediately begin running down his back. It hurt. Even by Yuuji’s fucked up pain tolerance standards.
Sukuna licked his claws, looking mighty pleased with himself. “The vow did not activate.” He smirked, four eyes staring smugly down at him.
“You don't need to fucking say it out loud, asshole.” Yuuji huffed, trying to not sound as wrecked as he already felt. Not like he could hide it. Their thoughts and feelings literally started blurring together when they had sex.
Sukuna’s mouth was rapidly turning his legs into jello. It was overwhelming in the best way and he felt too hot, too wrung out. Sukuna felt like a damn heater. The tongue that was wriggling around underneath him was dripping drool everywhere and crawling up between his cheeks again. The tip kept running over his ass, twisting and poking every chance it got. It was too big to just slide its way in there, but it was definitely trying its best.
Every now and then Sukuna ran his claws across a different part of Yuuji’s body or bit into him again. Prodded at the bite marks already there and licked up spilled blood. Yuuji's pain tolerance was so damn high that even feeling muscles slicing into ribbons wasn't enough to override the pleasure coming from between his legs. Just enough to make it sharper, make him cry.
Sukuna clung to his thoughts, following the rising jolts in his spine. The best part was knowing just how pleased Sukuna was to have Yuuji at his mercy. Fully vulnerable. Being torn to pieces and falling apart. If it weren't for their vow, and chasing mutual pleasure, Sukuna’s second mouth could quite literally consume him whole and there was nothing Yuuji could do about it.
The knowledge that the only thing keeping this from going very, very south was the fact that both of them getting off was funner for all involved? Was an adrenaline high that Yuuji still could barely believe when it came to having sex with Sukuna. It was thrilling. And Sukuna felt his excitement, took pleasure in it, and Yuuji felt that. The cycle just kept going in circles until sometimes Yuuji wasn't sure who felt what.
He came with a pathetic shout, eyes rolled back and legs kicking helplessly. His thighs were as stretched as wide they could possibly go to straddle the mouth.
Sukuna laughed. He bit at several of his own fingers, crunching off the sharp claws and a bit of actual flesh and bone too. Yuuji shuddered at the giddy feeling the pain caused. Sukuna loved pain of all kinds. It was extra weird to feel when they were bouncing back and forth so much.
With a bit of concentration, his fingers grew back but not the deadly claws. A small part of Yuuji sighed in relief. He could tell what Sukuna was planning on doing with those fingers and he'd been a little scared what those claws might do to his insides.
“What did I say? Have a little more faith in me.” Sukuna huffed, running that hand behind him.
Yuuji was starting to shudder and feel incredibly overstimulated, the mouth unending in its movements even as he softened. He whimpered and rested his head against Sukuna.
Sukuna sank a finger inside of him with little to no warning, pushing past with nothing but a truly excessive amount of drool as lube. Yuuji groaned at a high pitch. Whoever said don't use spit as lube definitely didn't take into account buckets of the stuff working perfectly fine.
It was still a lot. Enough to fill him up in an instant. Yuuji cried and couldn't figure out if bucking into the overwhelming heat or bucking back into the burning stretch was worse. He was trapped between two uncomfortable rocks and they were both hot. His face was warm and he could feel tears welling up in his eyes.
Sukuna just cackled, pausing only to lick the salt off his face before moving his finger. Yuuji could barely even squirm, held in place. His legs were weak and trembling.
“Good boy~” Sukuna rumbled.
Yuuji’s hips jerked, dick coming back to life just a bit. Damnit- there was nothing worse (or better?) than someone in your head and knowing all of your kinks. It gave Sukuna a fast track to getting Yuuji’s head in the game.
Being fucked between a single finger and a massive tongue as big as his torso, Yuuji really, really wasn't sure why that was possibly a bad thing.
Sukuna pulled his finger out to scoop up a bit more drool before starting to press two in. Yuuji whined. It burned.
“Relax, Yuuji, the more you fight it the worse it'll be.” Sukuna licked his face again. Yuuji was far enough gone he didn't even care how weird that was.
“Dunno if I can- relax much more.” Yuuji protested. Seriously, he was trying but everything happening kept making his muscles tense up instead.
“Tch. If I didn't know for certain you weren't, I'd think you were still a virgin.”
“D’you seriously gotta be such a jackass when you've got- agh! G-got a finger up my ass, dude?”
“Do you seriously keep calling me ‘dude’ when I have two fingers up your ass?” Sukuna snarled back, finally slipping both fingers in down to the last knuckle. Yuuji shouted and pressed his face into his chest, trying to breathe. Fuck that hurt. But fuck it felt good.
Knowing (and feeling) how much Sukuna liked both the pleasure and the pain, it was straight up euphoria. Yuuji’s head was swimming.
“There you go~” Sukuna grinned into his hair, scenting him. “Relax your body, stop fighting it so much, brat.” He pushed a heavy feeling over onto Yuuji that made his limbs feel impossible to move. An example, probably, though Yuuji had no idea where the fuck Sukuna would feel something like that. “From experience, dumbass. Now stop getting distracted.”
It was kind of hard! Yuuji’s head was getting kind of floaty as it got confused between the two of them. He felt so full and nice but also covered in pain and blood but there was a deliciously hot, wet mouth sucking on his entire lower half like a jollyrancher.
Those two giant fingers pressed further inside of him and Yuuji moaned. They brushed against a particular spot and he melted just a little. Sukuna rumbled and made sure to keep rubbing up against it, the two of them sinking closer together as the pleasure peaked through both of them.
Yuuji came again shortly later, shuddering, completely unable to move wrapped up in Sukuna as he was. He made a pathetic noise when Sukuna kept moving, milking him through his orgasm. The mouth underneath him drank up everything. Not like he could get even more of a mess than he already was.
Sukuna just kept fucking him, rocking back and forth, until Yuuji was a boneless pile against him and he was hard again. He could barely twitch his toes, hands clutching weakly at the tattoos in front of him.
Sukuna drew his hand back and into the drool, scooping up more. Yuuji whimpered when he felt the tips of three fingers at his entrance.
“You've got this, Yuuji.” Sukuna purred. “Such a good boy for me, aren't you? Just stay nice and relaxed.”
He pushed in with a forceful twist of the wrist. Yuuji cried. He was drooling against Sukuna’s chest, eyes closed as he focused on the sensations.
The stretch really, really fucking hurt. Yuuji could barely focus on the pleasure for a while as Sukuna wiggled his fingers and fucked them deeper and deeper. His face was wet and sticky. The mouth on him was unceasing.
Finally the stretch began to ease and he could feel Sukuna’s fingers brushing against his prostate again. Yuuji let out a garbled whine that might've been his name.
Sukuna chuckled and spread his fingers, making Yuuji’s vision go black and white. He stopped breathing for a moment.
Then they pulled out. Yuuji wheezed, feeling drool drip from his ass. He blinked a few times.
“I think you're ready enough, don't you?” Sukuna cackled.
“Whuh?”
His breath hitched as he was detached from the glorious heat at his pelvis. The tongue reached for him, trying to cling to him. Sukuna batted it away with one hand and a scowl.
One hand on either side of Yuuji, Sukuna settled him right above his cock.
“Shhhhiiiit…” Yuuji slurred, remembering what was about to go inside him.
“Don't worry, you can't die here, remember, Yuuji?” Sukuna licked at the salt on his cheeks and nibbled at his ear.
Yuuji whimpered. That might be the problem.
Then he was lowered, completely unable to control his descent, and he felt that massive head prodding at his ass.
Sukuna was surprisingly gentle as he rocked his hips back and forth, pushing his cock inside bit by bit. Yuuji’s head fell to the side limply, spine like jello.
“S-Suuuk-” His eyes rolled up in the back of his head. He swore he felt a pop as it pushed inside and stretched him to the fucking limit.
Yuuji was stunned silent, barely breathing, trying to adjust to the massive fucking dick inside of him. Sukuna growled delightedly and ran a hand up Yuuji’s back, tracing only the faintest of scratches into his skin.
“If I knew this was all I needed to shut you up, I would've fucked you properly sooner.” He bit Yuuji’s ear, shocking him out of his stupor.
“Fffu-” Yuuji was trying so hard just to keep himself breathing slowly and steadily.
“Yeah yeah, fuck me.” Sukuna sneered with a laugh. “More like fuck you right now, though, eh?” He twitched his hips and forced himself just a little deeper in.
Yuuji's hands scrabbled weakly at his chest, about as effective as a puppy. “Sssuuk-k'naaa-” He panted shallowly.
“You know what I like you to call me like this, Yuuji.” Sukuna growled, hands tightening on Yuuji’s hips in both promise and threat.
“R-Ryou-!” Yuuji gasped. “Ryou-”
Sukuna pulled him down on his cock at the same time he thrusted up and Yuuji wailed. Something definitely tore. He didn't fucking care. The combined pleasure and pain ricocheting across the two of them was mind blowing.
Pain. Stretched to the absolute limit, too large to even clench down on. Hot blood pooling somewhere inside. Delicious tearing and tugging as he sank deeper and deeper. Pleasure as every nerve sparked and blew. Hot heat over Yuuji’s cock as Sukuna’s mouth licked the front of his body.
They were lost. Sukuna thrust in and out, Yuuji went completely limp. He wasn't sure where one began and the other ended. It was pleasure and pain and seeking more of one to find the other.
Both feelings crested and swelled until it overcame them both and everything went truly, properly dark.