Be a good boy - Chapter 1 [NSFW]

“Don’t you wanna be a good boy for me?” Izuku asked, nipping lightly at Katsuki’s neck. “Come on, baby, talk to me.”

“It’s stupid,” Katsuki grumbled, squirming in Izuku’s lap. “Forget it.”

“It’s not stupid if it’s bothering you,” Izuku reminded him, hand trailing up the back of Katsuki’s shirt. “Was it the meeting with Aizawa?”

“Aizawa and the principal,” Katsuki grumbled.

“Wait, what? Why? What’s going on?”

Katsuki grumbled wordlessly, and Izuku bit down a tiny bit harder, just enough to leave a faint red mark on his skin.

“I’m bordering on being expelled,” he admitted finally, voice barely a whisper. “Aizawa doesn’t want to, but he’s already been advocating for me.”

“What? No way. Are you serious?”

“Mm. They wanted to kick me out last time I got in a fight, but Aizawa convinced them not to.”

“Kacchan, that’s serious,” Izuku complained, sitting up straighter and removing his hand from Katsuki’s skin. “They didn’t even tell you?”

“Mm. There were hints, I guess.”

“You care about rules more than anyone I know. Iida tried to murder someone in first year, what the hell?”

“He did what?”

“Never mind, forget I said that. But this is insane, Kacchan! We’re so close to being real, professional heroes together! They can’t kick you out when we’re so close.”

“They can. They will.”

“You can’t let them.”

“What the hell am I supposed to do? It’s not like I’m gonna magically change overnight, this is who I am. I yell at people and shit, that’s just what I do.”

“You don’t yell at me.”

“You’re different.”

Izuku huffed quietly, considering it, and finally gave him a stubborn nod.

“Alright, I’m gonna take care of it. I’m gonna help you.”

“You are not going in there, I don’t need my boyfriend fighting my battles.”

“No, I’m gonna help you,” Izuku explained. “I’m gonna help you to be good! We’re gonna show them you can do anything you set your mind to, including being nice!”

“Me? Nice? Yeah right.”

“Trust me, Kacchan! I have a plan!”

─────

Izuku was waiting on the bed when Katsuki got back to his room, leaning against his hands as he waited patiently.

"You were gone a while," Izuku mused, glancing at his phone. "I was starting to wonder."

"I didn't know you were waiting."

"I know."

He began to pull his Hero Costume from the closet to change, only pausing when he saw the smirk on Izuku's face as he watched his boyfriend strip.

"We don't have time," Katsuki insisted, as he threw his pants aside. "Don't start."

"I wasn't starting anything."

"Why aren't you dressed, anyway?"

"I am," Izuku countered, unzipping his hoodie a little to show the jumpsuit underneath. "The rest is in my bag."

"Why are you here?"

"I got you something. To go with your costume."

"You what?"

"Just a little reminder."

He produced a dark steel band, about as wide as his thumb, and fastened it snugly around Katsuki's neck.

"I'm not a jerk, you don't have to wear it all the time," Izuku clarified, when Katsuki's face burned red. "But when you're in costume, it's a little reminder from me. You belong to me, don't go getting carried away, you hear me? Gotta be a good boy for me."

"Y-Yes, Sir."

"Good boy. Come on, then, we'll be late for class."

He scooped up his backpack with the rest of his costume in it, throwing it over one shoulder, and Katsuki paused to look in the mirror on his way out. It didn't look particularly out of place with his outfit, didn't stand out, but he could feel the metal against his throat and he didn't know how he would get through class without blushing the whole time.

God, Deku was a jerk sometimes.

He followed awkwardly as Izuku led the way back to Ground Beta, meeting up with a group of their classmates on the way. He didn’t speak, barely grunted a hello, but no one seemed to think twice about it – Katsuki wasn’t much for small talk, after all. All Might was waiting for them at the other end, the rest of their class gathered around to chat while they waited for the last of the group to arrive, and still no one said a word about it, no one noticed the annoying new addition to Katsuki’s costume.

It was all he could do to not fiddle with it while All Might gave their directions for the day, doing his best to pay attention to the words but still so laser-focused on the thing, convinced someone was going to call him out at any moment. He was so conscious of the way it felt around his throat, but he knew the more he touched it the more likely people were to notice. If he could pretend it wasn't there – or better yet, pretend it had always been there – it was more likely to fly under the radar and not be mentioned by anyone else.

“Kacchan,” Izuku sang, as he sidled up next to Katsuki when they formed their groups. “You're blushing a lot today, what's going on?”

“Cut it out,” he scowled. “Don't start this.”

“Sorry,” he giggled, “do you want to be my partner?”

“Do I have a choice?”

“Not unless you already promised someone else, but it looks like Kirishima is working with Kaminari again, so I doubt you did.”

“Fine,” Katsuki sighed, “may as well, then.”

He stretched his neck lightly, admittedly a little impressed that the thing - he refused to call it what it was – didn’t pinch or catch on anything, the entire piece smooth and soft and slightly cool against his skin. It was guaranteed to be heat-proof, Izuku would never have made that mistake, which meant there was no reason it should ever get in his way or cause him any problems.

Well, other than the raging boner he was packing beneath his costume. His baggy pants and protective cup were enough to keep that under wraps, though. Katsuki nodded faintly, following Izuku to a clear space to get warmed up, but his face flushed bright red when he caught Izuku’s eyes wandering, looking down at the dark steel smugly.

“Don’t start,” Katsuki grumbled. “Just fight me, asshole.”

“Calling me names isn’t a very good start, Kacchan.”

“Maybe if you beat me I’ll stop.”

“You’re on.”

─────

“How do I take this thing off?” Katsuki questioned, examining his new collar in the mirror.

“Oh right, that. You can't.”

“Excuse me?”

“I can, though,” Izuku grinned, holding up a tiny key that would undo the latch. “When I'm ready to.”

“You've got to be kidding me.”

“If you're a good boy I might give it to you on days when we have heroics in the middle of the day, so you can change without me, but if you're naughty you'll just have to wait for me to do it all the time.”

“Deku, come on.”

“It's okay, it locks automatically, so you can put it on without my help.”

“That's not what I was complaining about!”

“Good boys don't complain.”

Katsuki froze, burning red, and finally turned his gaze to the floor.

“Are you gonna do this forever? After we graduate and shit?”

“That depends if I get bored or not,” Izuku laughed, nudging Katsuki's chin up again to make him meet his eyes. “And if you're good or not. How about a little test for today?”

“Do I have a choice?”

“That's not a good start.”

“Sorry, Sir,” Katsuki said flatly, dripping sarcasm. “That sounds perfect.”

“Much better. Question number one, what is the most important thing a hero should be?”

“Strong.”

“Bzzzt. Try again.”

“Strong, Sir.”

“Not what I meant,” Izuku smirked. “But better.”

Katsuki contemplated for a moment, pulling a face.

“Good, Sir.”

“Ding ding ding. Question number two: What makes someone good?”

“Being... Helpful. And... Nice. Sir.”

“Good answer. Question number three: Is Kacchan helpful and nice?”

“Not often,” he admitted.

“Ergo, is Kacchan good?”

“Not really.”

“Can Kacchan be a top hero if he isn't good?”

“No.”

His gaze sank to the floor again, and Izuku leaned in to kiss him lightly.

“You're good when you try to be,” Izuku assured him, clicking his key into the little lock. “You mean well, even if other people don’t always see it. You'll get there.”

When he took away the collar, Katsuki almost missed it. He'd gotten used to the weight of it around his neck, even after just one training session wearing it, and Izuku kissed his throat where he could still feel the phantom sensation.

“When you're wearing it, you're going to be good, aren't you?”

“Yes, Sir.”

“And when are you going to wear it?”

“When I'm in costume.”

“And?”

“And probably in bed sometimes.”

“I was looking for 'when I tell you to' but that's a good one too,” Izuku laughed. “So when you're in costume, you'll remember, right? You'll remember to be good.”

“Yeah.”

“Good boy.”

As much as he hated to admit it, something about Izuku talking down to him made him hard. He wasn't sure exactly which part it was – the powerlessness or the firmness or the praise – but something about it drove him insane, even if he couldn't – wouldn't, for that matter – put it into words.

“Is something bothering you, Kacchan?”

“Not really.”

“Do you want to talk about it?”

Katsuki nodded faintly. Even though he couldn't physically say 'yes, I want to talk', Izuku always knew. He didn't push, just waited patiently, still drifting kisses down Katsuki's neck and chest.

“What should I do?”

“About what, Kacchan?”

“To be... Good.”

Izuku paused for a moment, smiling to himself, amused by the flush to Katsuki's face.

“You really want my opinion?”

“Yeah. I know there's probably a lot of stuff, but... Well, people say it a lot. That I need to be better or nicer or whatever. People tell me I'm riding the line between hero and villain, and I don't want that. I want it to be clear.”

“Other people have said it?”

“Well... A few, yeah. Like my first internship.”

“Oh. Yeah, they wanted you to just completely change who you were to be like them, that wasn't cool.”

“You don't agree?”

“I don't think it matters what you look like, they were weirdly fixated on that. Your actions speak far louder than your appearance. Your look suits you, and your costume and everything seem very strong and heroic to me. Besides, the school wouldn't have given it to you if it didn't look hero-y enough.”

“I guess not.”

“But you can't fix the problem in a day. You just have to take baby steps and hope people notice the effort, hope that over time people start to see you as a better person. We can all be better people, don't get me wrong, I don’t think you’re a bad person. But we all have to strive to be good, all have to continually try to improve.”

“Some people do it so effortlessly. You, for one.”

“How many times have I done stupid things based on my own ego? Rushed into battle unprepared, fought when I should have left it to the professionals, or run off to try and handle things myself instead of letting people help. That's not good, I need to work on it too.”

“You did it for the right reasons, though.”

“So do you. I see you trying, in your own way.”

“Yeah?”

“Mm-hm.”

“Okay. I guess... I guess that's good. I am trying.”

“I know. Now, are we gonna fuck or what?”

Katsuki's head snapped up, and when he saw the smirk on Izuku's face he grinned, all his worries forgotten when he smashed their lips together in a hurry.

“Such a good boy for me,” Izuku whispered against his lips. “So proud of you, Kacchan. You worked so hard today.”

Katsuki whined quietly, tilting his head when Izuku began trailing kisses down his neck, and as Izuku’s warm hands slid up his shirt he knew he would agree to just about anything to keep it going. Izuku seemed to know that too, judging by the way he gently caressed Katsuki’s chest muscles, occasionally brushing a thumb over his nipples and making him squirm.

“You’re gonna be so good for me, aren’t you? My good boy?”

“Yeah,” Katsuki agreed breathlessly. “Always.”

“Mm, I know, Kacchan is such a good boy. You learned so fast, got so good at doing what I ask.”

“Want rewards,” Katsuki grumbled, blushing.

“Yeah, only good boys get rewards,” Izuku grinned, sliding one hand down to rub at Katsuki’s clothed crotch. “Kacchan learned that very fast.”

Katsuki’s breath hitched when Izuku squeezed gently, pressing against his aching dick, and when the teeth bit down on his neck again he couldn’t hold back a moan.

“So, my good boy,” Izuku continued, kissing the little bite mark tenderly. “Tell me what you’re gonna do differently tomorrow. What are you gonna do to be a good boy for me?”

“Mm... Like what?”

“Uh-uh, I’m not giving you the answers, you’re my smart baby, you can think of something.”

He sucked at Katsuki’s neck, and Katsuki bit back another moan, gasping for air as he tried to think – his head felt empty.

“I’ll... Work hard.”

“You always work hard, Kacchan. My baby is a very hard worker, we know that. But he needs to be good too, right?”

“Mm... I’ll... Shit.”

“Yeeees?”

“I... Won’t yell.”

“At all?”

“At people,” he clarified, gasping. M-Maybe if- Shit. If they’re gonna get hurt. But not... Mean yelling.”

“That’s a good goal,” Izuku agreed, unzipping Katsuki’s fly. “Well done, baby. You’re gonna be so patient, yeah? The best, most patient hero ever.”

“Yeah,” Katsuki agreed, relieved to feel his cock finally spring free. “Patient.”

“That’s my boy.”

Izuku bent over, wrapping his lips around Katsuki’s head, and Katsuki finally gave up on thinking. He stopped holding back his moans, stopped trying to come up with words, to say, just let Izuku push him gently onto his back and swallow him down greedily.

Fuck, he’d do anything if it meant Izuku would blow him.