[NSFW!!!] 8 Simple Rules (for screwing my Childhood Friend) - Chapter 4

Chapter 4: "No making fun of each other's kinks"

Izuku fought with himself as he stared at the text, pacing back and forth across his bedroom like it was the hardest decision he'd ever made. One text, one sentence, one wrong word could make or break his entire arrangement. He liked their meet ups, liked the passionate, experimental sex they had, liked the way they seemed to complement each other so well in the bedroom. Where else was he going to find someone who liked to be ordered around the way Katsuki did? Where else was he gonna find someone with biceps that could crush his head with one wrong move and pecs that he would literally die for? Where else was he going to find-

No, this would work, it had to. He really didn't want to go back to jerking off in the shower, straining to stay silent so no one would catch on. 

Katsuki wouldn't care, right? Izuku would make it fun for him. Maybe he should add that to the text? "Come to my room, there's something I want to try, please don't freak out, I know it's weird as fuck and you'll never look at me the same way again but I'll make it fun for you."

Sure, that would work.

He sighed as he erased the entire message again, staring at the blank screen, messages deleted frequently to avoid mishaps with his friends. Just the name remained, the happy little "Kacchan!" at the top of his screen. He saw that name there far more often than he should, considering how rarely they talked outside of class.

> I have a suggestion for rule 4

Send.

There, that would at least get him assurance that it was a good time to talk. He could only imagine how awkward it would be to blurt out the words while Denki and Mina looked over his shoulder without a care in the world. 

> Better not be lame.

Did that mean he wanted to hear it?? Was he stalling?? Was he trying to be inconspicuous?? God damn it, Kacchan! Why did he have to be so cryptic??

> Hit me.

Thank God.

He finally relaxed a little, leaning back into his pillows, as he typed out the words he had practiced so many times in his head, making sure it was absolutely perfect and clear before he even considered mentioning it to Katsuki.

"No making fun of each other's kinks."

The room went eerily silent as the little icon popped up to say it had sent. Katsuki would have seen it right away, he never put his phone down mid-conversation unless he'd just told you to fuck off. Why wasn't he answering? Was he regretting their arrangement already? Debating how to break it off without hurting Izuku's feel- Okay, no, that was a stretch.

A solid five minutes passed, and Izuku watched every one of them tick by in the corner of his screen. Why did he ever think this was a good idea?

The knock on the door made him jump near out of his skin, stumbling to his feet and losing his phone underneath the bed immediately, spitting curses as he hurried to the door. His face burned bright red as he prepared his apologies and excuses, tearing open the door and almost slamming it into his own foot.

"This I've gotta hear," Katsuki smirked, arms folded across his chest.

"K-Kacchan!"

"Out with it, nerd," he demanded, nudging his way into the room and letting the door swing closed behind him. "What dumb thing do you want so bad that you have to make it a rule that I can't make fun of it?"

"I'm not saying anything unless you accept the rule," Izuku mumbled, shuffling back into the room as Katsuki sat down heavily on his bed. 

His hands looked extra tan where they rested on the pale blue of Izuku's Official-All-Might-Fan-Merch bedsheets, Katsuki switching immediately from the arrogant smirks to something a little softer, leaning back as he watched Izuku with curiosity.

"You want to make a list or some shit?"

"Can I?!" Izuku's eyes shone, and Katsuki immediately regretted asking. "An official contract?!"

"Fuckin' nerd," Katsuki sighed. "Fine, but keep it well hidden from your nerd friends."

"Oh, we don't really hang out in here, but yeah! I will!"

He dug out a notebook, carefully tearing a piece of thick paper from the middle and laying it on his desk, then reached for his favourite pen. Katsuki just sighed as he watched.

"One:" he mumbled as he wrote. "What happens in the bedroom, stays in the bedroom."

"Most important one, if you ask me," Katsuki forced out, his cheeks tinted pink. "Don't tell anyone I'm..."

"A bottom?" Izuku asked, completely straight-faced. "Or a sub?"

"Yes."

"It's nothing to be ashamed of, everyone has their preferences," he shrugged. "Okay, two. No questions asked. And three was... How did we phrase it in the end? Did we talk about that?"

"Whoever falls in love first, loses."

"Is that really a rule, though? It's more like a contest."

"Fucking write it, nerd ass."

"Okay, okay, writing."

"And four," Katsuki said softly, in a tone none of his friends would even recognise as him. "No making fun of each other's kinks."

"Yeah," Izuku smiled, relieved. "You promise, right?"

"I'll sign the bottom if you really want."

"Okay!"

"I should stop making sarcastic offers around you," he sighed, hauling himself to his feet and snatching the pen. "Stupid nerd."

"I'll make it fun for you," Izuku blurted out, Katsuki's signature wobbling for a moment. "I mean, if you're super against it then we won't do it, but if you're just kind of like 'yeah whatever' then I promise I'll make it fun."

"What is this mysterious nerd kink of yours, huh?" Katsuki asked, flicking him in the forehead. "You're not fuckin' shitting on my chest."

"What? Is that a thing?"

"Ugh, your friends must have such normal conversations compared to mine."

"Why? What do you guys- You know what? I don't think I want to know."

"So it's not that, then. Is it the sweaty crotch thing? 'Cos I showered like an hour ago so you're shit out of luck."

"No!"

"It's fuckin' feet, isn't it?"

"Please stop guessing, Kacchan."

"So it is feet. You lame-ass vanilla shit, that's a baby kink. Sex 101: Introduction to Kinks."

"It is not feet."

"Then tell me."

"I will if you shut up for all of five seconds!" Izuku burst, burning crimson. "You're not making this easy, Kacchan!"

Katsuki smirked up at Izuku, leaning back a little more as he spread his knees wider. 

"I thought you liked teaching me how to behave, Master."

"You're fucking horny, aren't you?"

"Incredibly."

"You're... Wow. Just wow, Kacchan."

He sighed, taking a moment to compose himself, and Katsuki waited with a surprising level of patience. Still that conceited little smirk stayed on his face, and Izuku took a step closer. Then another. He took a deep breath and leaned in close, pressing his freckled cheek against a warm, soft one, and paused once more before his lips moved.

"Get on your knees where you belong, and I'll show you."

"You gonna make me?"

"You don't want to see what happens if you disobey me."

Katsuki smirked, but levered himself out from under Izuku all the same, a sarcastic look on his face as he dropped to his knees.

"Alright, nerd, you feel better about yourself now?"

"Keep talking, Kacchan. I love seeing you eat your words."

He reached into his desk drawer for a little black bag, clutching at it with shaking fingers. Katsuki still watched him, with a weird combination of curiosity and challenge mingling on his features. Izuku bent down slightly as he emptied the bag into his hand, blushing again when he felt the smooth fabric and the sheer weight of the thing in his hands for real. 

"Haah?" Katsuki protested, when Izuku reached for his neck. "Seriously, shithead? You get off on treating me like your pet?"

"But you are, Kacchan," Izuku responded immediately, his confidence returning a little when Katsuki didn't move to stop him. "You're my good boy, aren't you? Now everyone can see who owns you."

"Fuck," Katsuki hissed, shifting a little on his knees. "Don't say it like that, asshole."

"I'll say it however I want," Izuku smirked, his hands steadying as he fastened the dark leather, making sure it wasn't too tight around Katsuki's neck. "What are you gonna do about it, hmm?"

"Don't try me, Deku."

A scarred finger hooked through the metal loop at Katsuki's throat, pulling him in sharply and making him stumble for balance.

"Want to try that again, pet?"

Katsuki's eyes were wide when he looked up, and for a moment Izuku hesitated, bringing his free hand up to cup Katsuki's cheek. 

"Safe word?" he asked. "You remember it?"

"Fuckin' obviously."

"Tell me."

"Fucking Katsudon, asshole, why do you feel the need to make me say it every time?"

"Because you'd be too proud to admit it if you forgot what it was. This way I know for sure."

"Asshole, like I'd forget."

"Just do what I say, Kacchan. It only takes a minute."

"Fuck you."

"You can never make this easy on me, can you?"

Katsuki grinned, eyes flashing as they met tired green.

"Would that be any fun?"

Izuku turned, dragging Katsuki back to the bed, ignoring the stumbled protests it came with as he shuffled awkwardly on his knees. He sat, hauling Katsuki across his lap, easily halting the squirms with one strong hand on his shoulder blades.

"Touch it."

"What?"

"Put your hands on your collar. Touch it. Feel it."

Izuku was a little surprised when Katsuki behaved, but sure enough his fingers came to rest on the thick leather Izuku had spent so much time picking out online.

"Keep them there until I say you can move."

"Or what?"

The retort came with a lot less bite than the first few, and Izuku smirked to himself.

"Or I'll take it away and give it to someone who appreciates it."

Katsuki's grip tightened a little, and immediately Izuku knew he'd won. All the protests, all the teasing and smirking, but Katsuki liked this idea.

God, this was gonna be fun.

He pulled Katsuki's pants down to expose his little ass, experimenting with a tiny burst of power in his palm as he brought it down on Katsuki's skin. Over his lap, the body shuddered through a gasp, and Izuku pushed him down again when he squirmed against Izuku's thigh.

"Tell me, Kacchan, what do you think is a fair number for how naughty you've been tonight?"

"Fuck off."

"Well that just doubled it."

Katsuki squirmed a little, but Izuku knew it wasn't a real attempt at escape. No, he was pressing himself far too heavily into Izuku's hand, rather than try to slip away. Katsuki was a lot of things, but he wasn't stupid. Every time he squirmed straight into Izuku's touch, Izuku knew. He just wanted to feel it, wanted to feel overpowered like the horny little sub he was.

"What do you think is a fair number, Kacchan?" Izuku asked again, letting lights flash from his hand that made Katsuki tense up in a hurry. "Maybe one for each time you answered back?"

"Do you have all night?" Katsuki snorted.

"Oh, believe me, I really do."

Katsuki didn't answer, stuck for a retort as his mind wandered, and Izuku smirked as he rubbed at the fading pink handprint. 

"I'm letting you decide, Kacchan. I want to know what you think would be a good punishment for being such a little brat."

"Three," he said finally, not raising his head from where it hung near the floor.

"Just three?"

"Three but with ten percent."

"Believe it or not, I want to keep your ass intact, Kacchan. Let's try three with one percent for now."

"What do you think I am, a pussy?"

"Pretty much," Izuku grinned. "You underestimate how strong I am, Kacchan. One percent, three times, and I'll show you just how easy it is to make you submit to me."

Katsuki shuddered, but nodded all the same, and Izuku raised his hand again, holding Katsuki down firmly before he struck him across the same cheek once more.

"One," Katsuki choked out, as Izuku rubbed at his skin firmly.

"Such a good boy, I didn't even have to tell you," Izuku grinned, watching the face below him flush pink. "You're learning."

"Two!" he gasped, as Izuku spanked him again, on the other side this time. "Fuck!"

"Language, Kacchan. Rule Five, no foul language."

"Fuck that. You think it's gonna be sexy to hear 'please put your sausage in my opening'?"

"I could just gag you, then you wouldn't have to say anything at all."

"Fuck off."

Izuku slipped two fingers between Katsuki's lips, pressing in deep and feeling Katsuki swallow around him awkwardly. 

Well, that certainly shut him up.

"Practice," Izuku demanded. "Learn to be a good little fuck toy for me."

Katsuki whined, flooding red, and Izuku took the opportunity to spank him a third time, a little harder, watching both cheeks glow as red as his face.

"I didn't hear a number, guess that one didn't count."

"Ffuvknoyiu! Fuvknin dee!"

"Sorry Kacchan, can't hear you."

He slapped the burning skin again, Katsuki jolting underneath his touch, and felt him hum quietly around the long fingers.

"Still nothing? Hmm, interesting."

A fifth slap, and this time the response was a full-blown moan, making Izuku smirk. Finally he took his hand out, wiping the spit on Katsuki's cheek, despite the scowl he got for it.

"Fucking three," Katsuki hissed, as Izuku pulled him up by the collar. "Asshole."

"Now, now, Kacchan, don't ruin it. You were being so good for me a minute ago, counting nice and loud and keeping your hands on your collar. It's nice, isn't it? I picked it out just for you, Kacchan, did you know? I didn't have it just lying around in wait, I spent hours deciding which one would look best on you. I was right, too. You look so good, Kacchan."

Katsuki blushed, looking away and letting Izuku pull his shirt over his head to cast it aside. His pants still hung around his knees, but with the way he half-lay across Izuku's lap, he couldn't exactly do much about it.

"Sit on my lap, pet. I want to look at you."

He waited for Katsuki to begin to sit up, then dragged one of his legs around to straddle Izuku's thigh, his dripping dick pointing straight at Izuku's chest. He didn't seem to mind, didn't even really seem to notice how hard it was, just continued to scowl and avoid the slightly menacing gaze aimed at him.

"Look, Kacchan," Izuku instructed, pointing at the wall off to his side. "Look how good you look like this."

Katsuki obediently turned his eyes to the mirror, a little ashamed of the expression he saw, the flushed skin and wide eyes and messy hair, and of course the wide leather strap around his neck, thick and black, lined with silky fabric to match, only the silver of the buckle and loop breaking the stark pattern.

"You like it?" Izuku asked, when Katsuki tilted his head a little to clear his line of sight. "It looks good on you, Kacchan. Even better than I expected."

"What's this shit?" he demanded, touching a silver tag dangling over his throat. 

"Just tells everyone who you belong to," Izuku teased. "In case you get lost, you know?"

"Fuck off."

Izuku giggled to himself, and somehow it seemed to soften Katsuki a little, his touch becoming more gentle as he examined his new toy. Izuku slid his hands under Katsuki's thighs, lifting him up despite the jolt of confusion and the half-hearted protest it brought on, and happily he carried Katsuki closer to the mirror, where he could inspect the little silver tag.

"Fucking 'Kacchan', of course you did," Katsuki sighed, rolling his eyes at the bold letters engraved in the front. "I thought you might grow out of that shit one day."

"Never! It's such a good name! It sounds weird if I say your full name."

"Yeah," Katsuki acknowledged. "It does."

He flipped the tag over to see the back, scowling when he found the tiny letters.

'Property of Midoriya Izuku.'

"I belong to you now?" he asked, eyebrows knitting together. "You think you're my fucking owner?"

"Am I not?" Izuku grinned, turning so Katsuki's back pressed against the wall, holding him tight as he leaned in to bite the pale skin of Katsuki's neck. "I'm pretty sure I said you were my pet, did I not?"

"Fuck you."

"Aren't I your Master, Kacchan? You've said it enough times."

"Fuck you."

"Not with that attitude."

"Ugh."

"I could fuck you right here if I really wanted," Izuku teased, shifting one arm a little further to brush his fingers over Katsuki's hole. "It's not like you could do anything about it."

"Do it."

"Is that how we get what we want?"

"Do it, Master."

"Wow, you really are horny today."

"Are you gonna fuck me or not?"

"Eventually, if you're good."

"What do you fuckin' want from me?"

"Quit making demands, would be a good start."

Katsuki froze, contemplating, and Izuku grinned as he nipped at Katsuki's neck again.

"I know you want to be good, Kacchan. I know you like being good. You know what happens if you're good for me?"

"What?" he asked, immediately kicking himself for it.

"You get so much praise, Kacchan. I'll tell you just how amazing you are when you're being good."

"Shut up."

"You don't want to hear it? Don't want to know how gorgeous you are with that sweet look on your face when you're following orders? All soft and lovely instead of your usual scowls?"

"Shut up."

"I like it so much, Kacchan. I like seeing how your eyes glaze over and your perfect little lips part so those beautiful moans can come out."

"Stop."

"And I like the way those big perfect hands that destroy villains without a second thought end up clutching at the sheets and pillows for something to hold on to, like you can't control your own body."

"Stop."

"If you say it again, I will."

Katsuki fell silent, and Izuku smirked into his neck, licking at the little indents left behind by his teeth. They stood out against the dark collar, glowing red, and Izuku wondered if he could ever get away with leaving a real hickey for him to find in the morning. Maybe in winter, when he could cover it easier. Would their arrangement even last that long?

Yeah, it had to.

"What?" Katsuki grunted. "You're muttering."

"Sorry."

"Did I do something wrong?"

"No, Kacchan, of course not," he stroked at blond spikes, smiling softly at the grumble it earned him. "I was just debating how hard it would be for you to cover it up if I gave you a hickey."

"Don't," Katsuki said weakly. "I can't hide anything in my costume."

"Yeah, I thought maybe I'd do it a bunch in winter."

"F-Fine. Yeah. Whatever. Just not now."

"Not on your neck," Izuku grinned. "I'll have to mark up your thighs again."

"It's awkward to hide them in the changing rooms."

"You'll just have to change your pants in the toilet cubicle," Izuku rubbed his hand between Katsuki's legs firmly. "Or tell everyone what a little slut you are."

"No fuckin' way."

"They'd probably be happy, Kacchan. Do you know how many of our classmates would love to see you on your knees? Imagine if they could all just take turns with you, fucking your mouth or filling your little hole up nice and tight. You'd probably like that, letting them all use you like a toy. Feeling all those powerful quirks holding you down while they fuck you mercilessly."

"No," Katsuki protested weakly, squirming against Izuku's thigh. "They're not good enough."

"What was that, Kacchan?"

"I don't want loser-cock in my ass," he grumbled.

"What do you want, then?"

"You know what I want," he growled. "Someone who can hold me down even when I fight back, shithead. Stop making me say it."

"You don't think Kirishima or Todoroki could restrain you?"

"Like fuck if I'm gonna let half-and-half near me," Katsuki hissed. "And shitty hair wouldn't. He'd be too damn worried about hurting me or some shit, he'd never call me to his room with a collar in his hand."

"I knew you liked the collar," Izuku teased, flicking at the tag and listening to it jingle. "You belong to me, Kacchan. As long as this is on you, no one else is allowed to touch."

"Then fucking touch."

"You know what I want."

Katsuki let out a noise that seemed to be some weird combination of a whine and a growl, angry at himself for it even as the whine still escaped him. Izuku only smiled, pinching at the soft skin on his inner thigh, waiting patiently for Katsuki to cave.

"Please," he said finally. "Master, I need to cum."

"Interesting. What would you like me to do about that, hmm?"

"Own me."

"Good answer, pet."

In one smooth motion he switched his grip on Katsuki's thighs, turning him around to shove his chest into the wall. Katsuki turned his head, letting his cheek rest against the smooth, cool paint, praying for it to take away some of the heat in his skin as Izuku stripped the last of his clothing off without a word. Bare and open, he glanced back over his shoulder, watching as Izuku fought with his waistband with his free hand.

"I won't move," Katsuki found himself mumbling, blushing again when Izuku's eyes darted up.

"Okay, I'm gonna use both my hands for a second, then," Izuku nodded knowingly. "If you move even an inch it's gonna be another spanking, understand?"

"Yeah."

He hated to admit it, but he did seem to get his own way a lot faster if he did what Izuku told him to do. The damn jerk knew him too well, knew exactly how to torture him, making him be obedient like some shitty nerd-ass. He wanted to punch himself for staying put, for keeping his body flush with the wall while Izuku stripped, but at least the view was decent.

"There's my good boy," Izuku smiled, wrapping a gentle hand around each of Katsuki's wrists. "Up here now, okay?"

Katsuki nodded, letting Izuku bring his hands up over his head and press flat against the wall. 

"Feet apart."

Katsuki obeyed.

"There, perfect. Look at you, Kacchan. I've never seen anyone so sexy in my life. You're the pinnacle of jack-off material, I could just sit here and rub one out over and over looking at you."

"Touch me?"

He meant for the words to be demanding, but instead they came out more like a plea, his voice oddly high and whiny. If he were in middle school he'd have kicked his own ass by now, and he wasn't sure whether he was pleased by that knowledge or appalled. 

"Am I still an asshole?"

"Huh?" Izuku froze, staring at him in silence as he contemplated. "What do you mean, Kacchan? Why do you ask?"

"I know no one liked me in middle school," he admitted. "Am I better now?"

"So much better," Izuku assured him, his heart pounding as he leaned in close. "You're such a good boy, Kacchan. Middle school Kacchan would have gotten nothing but spankings and gags, he never would have been stuffed nice and full, never would have gotten his very own collar."

"I mean it."

"So do I. You were a silly kid, Kacchan, none of us are really proud of who we were in middle school. It's all in the past, okay? You're so much better."

"Okay," Katsuki breathed a sigh of relief, nodding. "You can touch me now."

In a moment of tenderness, Izuku wrapped an arm around Katsuki's waist, pulling him into his warm, scarred body. It still made him smile any time they got this close to each other, not for closeness or friendship or affection, but for the simple pleasure of the half an inch he'd gained on Katsuki in height. He'd never realised how tiny Katsuki really was, with the waist he could easily wrap one arm around and the height most of their classmates had already dwarfed.

"You're cute," Izuku teased, pinning strong arms in place to keep from being blasted. "So little, Kacchan."

"I'm not."

"We both know that's a lie."

For a moment they remained in their odd attempt at a hug, until Katsuki relaxed a little in his grip, and Izuku nipped at the skin around his collar again.

"You want me to fuck you, Kacchan?"

"Yeah."

"You sure? It's okay if you aren't in the mood."

"I can't move and I'm wearing a fucking collar. Do you not see my fucking hard-on?"

"Note to self: Buy restraints."

"Fuck."

Katsuki's dick dripped at the thought, and Izuku just smirked at him. He dragged Katsuki over to the bed, throwing him onto his back where he could keep an eye on those facial expressions, and quickly crawled over to pin him down.

"You go where I want you, Kacchan, don't go trying to arrange yourself."

"Fucking do it, then."

"Patience, pet."

Moving at a damn snail's pace, Izuku moved Katsuki's limbs one by one, slipping sweet-smelling hands under his hips both to keep them still and to prop him up a little, then leisurely prying his legs apart, knees bent toward the roof. Katsuki whined quietly the entire way through, but never once spoke a word of indignant protest, and when Izuku was satisfied, he leaned in to lick a perky nipple. 

"My good boy," he said softly, tracing the edge of Katsuki's pecs with his tongue, before he moved to the other nipple. "I like it when you behave, more than you know."

"Mmn."

"Do you know how pretty you are, Kacchan? I don't care what anyone else says, you're the prettiest guy I know."

"I'm a man," Katsuki grumbled, eyes darting to the side. "I'm not pretty."

"Oh, but you are. One hundred percent man, I know, just look at these arms." His hands kneaded at Katsuki's shoulders, feeling the tight muscles hidden beneath his skin. "But you're still fucking pretty."

Bakugou snorted, unable to resist a little smirk, and Izuku grinned back as he slipped himself between Katsuki's knees. 

"Ready to be torn apart?" he teased, pouring lube into his hand, right in Katsuki's view line. "I've had enough teasing, I just want to fuck you, so you've gotta be good so I don't have to stop, okay?"

Katsuki grumbled something, looking away, and Izuku raised an eyebrow as he guided the lube into Katsuki's anus. 

"Didn't catch that, Kacchan."

"If you want to fuck me, fuck me," he said again, a little louder. "Don't let me stop you."

"Oh Kacchan, you'd like that, wouldn't you?"

"Yeah."

"Then be good for me, because I'm not letting you cum if you're naughty."

Katsuki whined when Izuku shoved a finger into him, catching him off-guard. A few slick pushes then the second one joined in, stretching him nice and wide. Izuku had a strange knack for the motion: for efficiently and rhythmically opening him up, and for making Katsuki moan in the process.

"How," he choked out, when Izuku added a third finger. "How do you do this shit?"

"What's wrong, Kacchan?"

"Nothing," he hissed. "That's the problem."

"You want it to hurt more?"

"It's fine I just don't get it."

"Hmm... Ever considered that maybe you're just a slut?" 

They locked eyes, Katsuki's rubies flashing with stubbornness, but a quick thrust of Izuku's hand took away all thoughts of argument.

"I don't think I'm particularly good," Izuku explained, "I think you are just a sucker for having anything in your ass."

"Fuck you."

"Uh oh, am I gonna have to stop for Naughty Kacchan?"

"I'm not a sucker," he growled. "There's nothing wrong with liking anal."

"Oh, I'm aware, but that doesn't mean you aren't a massive subby whore for it."

He punctuated the three words with sharp thrusts of his fingers, and Katsuki moaned, clutching at the sheets as he arched his body up to take more, to take it deeper.

"See?" he teased, winding his free hand around the base of Katsuki's cock and holding firmly. "No cumming yet, Kacchan, I haven't said you're allowed."

"The fuck is that supposed to mean?"

"No cumming until I say so," he clarified, squeezing a little tighter and feeling Katsuki writhe, desperately trying to thrust against the fist. "If you think you're getting close, you've gotta either hold it or ask nicely."

"And if I cum anyway?" Katsuki challenged.

"Then I'll have to find you a nice tight cock cage so you can learn to control yourself. Little padlock with only one key, and guess who's gonna hold it, Kacchan? Because it won't be you."

"Fuuuuck."

"Maybe I'll hand it around our class sometimes, let you beg each and every one of your classmates and hope one of them will take pity and give it to you."

"No fuckin' way."

"I think it'd be super hot seeing you beg Todoroki to give you a key he doesn't even know the purpose of."

"Never."

"Or Kaminari, that one would be fun. He'd want to know what it was for, right? He would never stop asking you what the key unlocked."

"Stop."

"Unless you'd rather just be a good boy and beg me to avoid the whole problem."

"Fucking fine," he hissed. "I'll behave."

"Ooh, Kacchan." Izuku shifted a little, his erection grazing against Katsuki's hole. "Say it again, I like the way that sounds."

Katsuki opened his mouth for clarification, flooding red when he realised the words that had left his mouth, and immediately he snapped his jaw closed again.

"Say it, Kacchan. I'll fuck you when you say it."

"Promise?"

"Of course, Kacchan."

"Ugh."

He turned his head away, but Izuku dragged him back by the collar, tugging his head up off the pillow a little to meet his eyes.

"I'll behave," Katsuki repeated reluctantly.

"God, that sounds so good."

"And you thought the collar was the kink I'd make fun of."

"You signed the contract," Izuku grinned, pulling a little harder as he lined himself up, making sure Katsuki had a clear view of the swollen cock waiting at his entrance. "No making fun of me, remember?"

"I'm not," Katsuki grumbled. "You make fun of mine more."

"I don't! Just because I point out that you're a helpless, subby little bottom doesn't mean I'm making fun of you. I'm just stating a fact. You are, after all, aren't you?"

He released Katsuki's collar and waited right at the edge, rubbing his leaking tip against Katsuki's hole. After a long moment of silence, Katsuki nodded sharply.

"I'm a fuckin' sub and I'll fuckin' behave so just fuck me." His voice cracked, shuddering with the words, and Izuku smiled. "Please. Master. Fuck me."

"There he is," Izuku smiled, thrusting his hips forward to bottom out, letting Katsuki feel it burn. "My good little pet."

"Yes, yes, I'm your fucking pet," Katsuki moaned, throwing his head back against the pillow. "More, Master, more."

"God damn, was I teasing you that long?" Izuku chuckled, a little out of breath already. "What are you gonna do when you get close, Kacchan?"

"I'll ask. I'll wait. Whatever the fuck you want, okay? Just... Please."

Izuku couldn't resist that tone.

He began in earnest, slower at first to find the right angle, aiming straight for Katsuki's prostate by the time he lifted his pace. Katsuki panted beneath him, struggling to keep enough air in his lungs, but Izuku never once let up, abusing the same spot over and over, feeling the walls tighten around him, watching the contorted expressions that fought over Katsuki's face. 

"Please," Katsuki whispered, eyes squeezed shut. "I need it."

"Need what, Kacchan?"

"I need to cum."

"You think you should cum before Master?"

Katsuki shook his head, and for a moment Izuku wondered if he'd broken the boy, fucked away his argumentative nature.

"Can I, after?" he panted. "When you do?"

"Nicer than that, Kacchan."

"Please let me cum when you do. I want to cum together."

Izuku's heart skipped a beat, and he found himself nodding, even though Katsuki wasn't remotely close to looking.

"Together," Izuku agreed. "If you take too long, you miss out. You gotta cum when I tell you to."

"Okay," he nodded, teeth gnawing divots in his lower lip. "When you say."

Izuku pushed the strong thighs back toward Katsuki's stomach, admiring how soft and smooth they felt under his hands, barely a hair in sight. He wondered if Katsuki was naturally so bare, or if he took care of it himself – it wouldn't surprise him, really. Katsuki was picky about cleanliness, and Izuku wouldn't be surprised if Katsuki equated hair with being dirty. 

Maybe that was why he liked Izuku's cock, it was like a weird taboo with its nest of dark, curly hairs, Katsuki probably loved the idea of being fucked senseless with such a filthy dick. 

"Does the mumbling mean you're close?"

Izuku barked out a laugh, too out of breath to manage much more, but soon he was squeezing a little tighter at Katsuki's thighs, pulling him in to meet each thrust amidst a chorus of moans.

"Okay, Kacchan," he said with a little smile. "Cum for me, pet. Now."

Izuku could have sworn it began before he'd even finished his sentence, white spurts cascading over his chest and abdomen with a long, loud moan, and Izuku was right behind him, filling Katsuki with so much cum he thought he might pass out. 

For a moment they were silent, breathing hard to a strangely synced up beat, and when Izuku began to slip himself out, Katsuki's hole clenched. He milked out every last drop, holding it inside himself, and Izuku just smiled as he leaned over to nip at Katsuki's neck again, savouring the feel of the leather against his face.

"You're such a good boy, Kacchan. I love it when you behave for me. I've never seen you sexier than right now, just like this."

"Weirdo," Katsuki choked out, smirking. "No wonder you needed that kinks rule."

"If I'm weird, what are you?"

"Messed up and broken, probably."

"You're not." Izuku lay down beside him, stroking sweaty blonde hair back from Katsuki's forehead. "Not messed up, and certainly not broken."

"Not many people like the shit I like."

"A ton of people like the stuff you like, they just don't talk about it openly. If you announced 'hey, I'm a sub' in a room full of people, half of them would say 'me too'."

"Not happening."

"I know, it was theoretical."

He planted a tentative kiss on Katsuki's temple, half-expecting to be blown up for it, but Katsuki accepted the touch with a strange gentleness.

"I'm gonna hug you, okay?" he said softly, draping an arm across Katsuki's waist. "I don't want to go clean up just yet, so we're gonna stay here. Together."

"Okay."

"I'm gonna hold you just like this," he continued, hugging a little more firmly. "Until you're... We're, back to normal."

"The fuck is that supposed to mean?"

"Nothing, I'm just tired and out of breath."

"Yeah, me too," Katsuki conceded, letting Izuku pull him to his chest. "It was good, though."

"So good, Kacchan. So good."