This was inspired by a story I read earlier where there was an age difference between Izuku and Bakugou, though I think it was four years instead of two. But I wanted to write a scene where they interacted at school because I thought that would be interesting to see, so I did.

This chapter is just kind of the backstory to introduce them before we get to the good stuff.

"Wow, Kacchan!" Izuku exclaims, his eyes wide as he watches the miniature explosions in his friend's palm. "That's such an amazing quirk! I'm sure you'll make a great hero!"

Katsuki grins triumphantly. "Of course I will. I'll be the best," he boasts. Then he looks at the older boy across from him. "And I'll protect you, since you're quirkless and all."

Izuku frowns petulantly. "I'm not totally useless, Kacchan. I don't need you to protect me."

"Sure you are, Deku. But that's fine, because you have me. I'll protect you for the rest of our lives and you won't ever need anyone else," the blond proclaims.

"Careful, twerp," Katsuki's mom remarks from her spot on the couch, watching the two boys in amusement. "That sounds almost like a marriage proposal."

The face of the youngest Bakugou scrunches in thought as he ponders his mother's words. Then he nods, apparently reaching a decision. "Okay." He turns to his friend. "We're gonna get married then."

To his credit, Izuku only looks slightly confused. "But aren't we too young for that?" he asks, looking over at his own mother for confirmation.

She nods, amusement clear on her face. "That's right, sweetie," she agrees. "No marriage until both of you are adults, at the very least." Next to her Mitsuki lets out an amused snort.

"Oh," Katsuki says, looking mildly disappointed. Then he shoots Izuku a fierce glare. "Then you'd better wait for me, nerd. Got it?"

Izuku easily agrees. "Okay, Kacchan."

. . .

After all these years they still lived in the same neighborhood. It was only natural their paths would meet sometimes on their way back from school. Katsuki was glad this afternoon was one such occasion.

"Hey assholes!" he shouts, charging the two middle schoolers standing over his childhood friend and future husband. "Leave him alone!" At his fingertips small explosions crackle, just barely contained for the moment. He might've been a couple years younger than them, but he made a promise to Izuku and he fully intends to keep it. No one was going to harm his unofficial fiancé if he had anything to say about it, and he certainly did.

Unfortunately – or fortunately, for them – the jerkwads don't stick around much longer, no doubt scared by his display. Katsuki stops by his friend, huffing in disappointment as he watches the two run off. Then he turns to Izuku, who is gingerly picking himself up off the ground. He frowns but says nothing as he gathers his scattered things. Only after he had everything gathered did the older boy finally face his friend. "Thanks, Kacchan," he mutters quietly.

Katsuki says nothing for several moments. "What was that all about?" he finally asks.

Izuku shrugs and looks off to the side, avoiding the other's gaze. "They're just bullies; do they really need reasons?"

His eyes narrow in response. He may be two years younger, but Katsuki wasn't stupid and this wasn't the first time it had happened. "You were talking back to them, weren't you?" he accuses, catching the way Izuku scowls. "Stop doing that! It'll only draw attention to yourself when you can't do anything about it."

"That's not true!" Izuku is quick to snap back.

"You're quirkless; what were you expecting?!" Katsuki shouts in return.

"I don't need to have a quirk to do the right thing. I'm not just going to sit back and watch them pick on others," Izuku says.

Katsuki scoffs. "You should. That's not your problem."

"Then what kind of hero would I be if I did that?" Izuku retorts.

"You can't be a hero without a quirk!"

"Yeah? Then maybe I'll be the first."

Katsuki can't contain the snort at the other's words. "Like that'll happen."

"Watch me." Izuku's eyes narrow in challenge as he speaks.

Katsuki growls. "Fine."

"Fine," Izuku agrees, and with that he turns and continues his walk home, not once looking back at his friend.

Katsuki is stunned still for a moment, watching the older boy leave. He waits there for several more minutes scowling angrily in the direction the other disappeared. That was the same way he walked home, but he didn't want to think the other was following him.

They see each other a couple of times over the next few days – unavoidable, with their proximity – but neither says a thing and they pass by in stubborn silence. Izuku's mother dares to comment on it one day when she's with Izuku and notices, but drops the topic after Izuku remarks something about, "stupid, pigheaded Kacchan."

It lasts for a whole week – the longest Katsuki has gone without speaking to his future husband in years – before he finally breaks and makes his way to the Midoriya household, banging on their door as if he were forced to be there instead of having walked over of his own volition. Midoriya Inko answers the door, quirking an eyebrow at Katsuki's presence but she lets him in easily, informing him that Izuku's in his room. He gruffly thanks her and makes his way to Izuku.

He doesn't bother knocking on the door, opening it wide with no reservations. Izuku looks stunned initially to see his friend there, but he soon gathers himself and replaces it with a stubborn look of defiance. "Kacchan, what are you going here?" he asks, his voice holding none of the familiar warmth Katsuki has grown used to over the years.

Katsuki scowls and makes his way over to the other boy under his watchful – and suspicious – gaze. It takes him several moments to work out what he came there to say. "I don't want you to get hurt," he begins, to the other's confusion. Izuku opens his mouth to interject but Katsuki steamrolls right over him. "I don't not want you to be a hero, because being a hero is awesome. And I'm gonna be a hero and protect you, but I can't when you go out and pick fights you can't win. So stop it." Then he looks at Izuku expectantly.

The older boy sits there silently, his mouth still hanging open as he regards his friend. Then he closes it and shoots Katsuki a confused look. "I'm not going to stop trying to help people." Katsuki nods once in agreement, because saving people is a good thing. "…But I'll try not to get into fights?" Izuku finishes, more of a question than a statement. Katsuki nods again.

Izuku returns the gesture as he realizes what Katsuki is trying to say, a pleased smile turning up his lips without much thought. "If that's what you were worried about you should've just said so, dummy."

"Shut up, Deku!" the younger boy immediately snaps. "I'm not worried! You're just stupid for going and getting yourself beat up for no reason, then making me save you!"

Izuku can't keep the grin off his face. "But you promised."

"Yeah, but you don't have to make my job harder!" Katsuki gripes. "Jeez, ungrateful loser," he scowls, crossing his arms petulantly across his chest. Still, Izuku notes the light dusting of red on his cheeks.

"Okay then," he agrees, "I'll try not to get into anymore fights."

"Good." Katsuki nods.

. . .

The Midoriya family is invited over for dinner one evening. A common enough event for the two households, since they're all good friends that enjoy any and all excuse to get together and have fun. Katsuki's first year of middle school, and Izuku's last, is a good enough reason.

"So, Izuku," Katsuki's mom begins once they've had a chance to begin their dinner, "what high schools are you planning on applying to? You always wanted to go to UA, right?"

"Ah," Izuku remarks, fidgeting in his seat as his gaze quickly cuts to Katsuki right next to him – noting the boy's narrowed gaze – before looking back at his plate. "Yeah, but I'm not so sure anymore. I mean, I could always go into the General Studies track, but I feel a normal high school would be better suited for that, you know? That way I wouldn't be too close to all that hero stuff, and the sports festival is always a big deal that I'm not sure I really want to be involved in. I mean, that stuff looks like way too much for someone like me, haha…" he trails off, realizing he was babbling nervously.

Mitsuki didn't look at all bothered. "So a closer private school, probably. Do you know what you want to study?"

"I-I'm not too sure just yet," he replies, poking at some of the vegetables on his plate. "I was thinking maybe psychology, or perhaps criminal justice. But I'm not sure yet."

"Oh, so did you want to join the police force?" Katsuki's father asks, interested.

Izuku shrugs. "Probably."

"Well," Masaru begins, tucking back into dinner, "you've got some time before you need to decide for sure. No need to rush."

"I know I'm going to be a hero," Katsuki interjects, grinning first at his parents before turning to Izuku. "I'll be the best fucking hero ever, even better than All Might!"

Izuku smiles at his friend, only slightly playful as he remarks, "Maybe, though All Might is the greatest superhero ever."

Katsuki scowls at the older boy. "Hey now. As your future husband you should be saying that I'm the greatest superhero ever." Izuku flushes at that, as he always does when Katsuki talks about their future together, and it makes him grin even more.

"Ka-Kacchan…" Izuku mutters.

"I'm not hearing any disagreements, Deku," he responds.

"Kacchan!"

. . .

When Izuku had told Katsuki that he would do better to avoid getting into fights he'd meant it, really, he had. But Kaori-chan had been the closest to a friend he'd had in middle school – besides Kacchan – and he couldn't just let the sludge monster take her. Before he knew it he was charging in, throwing his backpack in the best attempt at a diversion he could come up with. But it serves its function and soon enough All Might is stepping in and the whole ordeal is over within seconds.

Later that evening, after All Might tells him that he can give him a quirk, Izuku feels like it's been one of the best days of his life – and he only feels marginally guilty thinking that because it was likely the opposite for Kaori-chan. Then he gets home and Katsuki is waiting for him. He looks angry and Izuku suddenly remembers what he promised with a wince. Katsuki says nothing as he leads the younger boy to his room, his mother wise enough to leave them well alone when Bakugou gets in his moods like this. Izuku takes a seat on his bed and waits patiently for the lecture he knows is to come while Katsuki paces. Still, he can't find it in himself to regret his actions.

Finally Katsuki explodes. "What the ever-living fuck were you thinking!?" he shouts, righteously angry. Izuku winces even so. "I mean – just – what the fucking hell!? You had no fucking reason -"

"My friend -" Izuku tries to interject, but Katsuki is having none of it.

"Yeah, I get that, you wanted to save her. Whoop de fucking do. But this isn't some shithead bully!" he shouts, rounding on Izuku. "That was a real villain, Deku! An actual villain that was doing some major damage that could've hurt you! Or worse, killed you! Did that not occur once in that thick fucking skull of yours!?" Kacchan turns his head away, and when he speaks again his voice is tight, as if he's struggling to keep it even. "Do you not realize what would happen to your mom if you died? To me?!"

When Katsuki finally looks at him again Izuku is horrified to find tears gathering at the corners of his eyes. He'd never known Kacchan to cry, no matter how injured he got or how upset he was. His surprise had him frozen in place, completely stunned.

"You idiot!" Katsuki shouts, oblivious to Izuku's internal shutdown. "You goddamn moronic shitty bastard Deku! I'll never forgive you if you died!" And then Izuku is being smushed against a firm chest as Katsuki wraps the other in a tight hug, his arms locked around Izuku's shoulders. He's shocked still yet again as he realizes Kacchan is hugging him, probably for the first time in many years. It takes a moment to respond before he's wrapping his arms around the younger's waist.

He can just barely hear the quiet sniffling of the other as he struggles to reign in his emotions, and if Izuku feels any dampness on his shoulder he doesn't bring it up. Instead he rubs a soothing hand up and down the span of Katsuki's back he can reach in an attempt to comfort. He really hadn't meant to worry his friend so much and it almost physically pains him to see the other so affected. "I'm sorry," he says, because he is. "I'm sorry I made you worry so much."

"You're damn right you're sorry," Katsuki growls into the older boy's shoulder, still not quite ready enough to let go. His emotions had been wrangled, but the fear of almost losing Izuku had deeply rattled him and he still needs the physical reassurance that the other is okay. Not that he was going to mention this to the other – though he had a feeling he was already aware. "But if anything like this ever happens again I swear I'm fucking chaining you to my goddamn side so you can't get into anymore trouble."

Izuku huffs out a laugh, though he has a feeling the other isn't entirely joking. "Alright."

"Just fucking watch me."

"Okay."

"I swear I will."

"I believe you."

"Shitty Deku," Katsuki scowls, finally pulling back to look at the other. The corner of Izuku's lips are quirking up in an amused grin that only serves to get on his nerves even more. On impulse – and partly out of spite – he leans forward and presses his lips against the others in a chaste kiss before pulling back, enjoying the way Deku's face explodes in red.

"K-Ka-Kaachan!" Izuku squeaks, his hands coming up to cover his face. His eyes are wide as he looks at Katsuki, and that's when it really hits him.

He just kissed Izuku.

I mean yeah, he's been proclaiming to their families and others that the two of them are going to be married in the future, but so far those have just been words. And sure, he and Izuku might've been pretty close, but they were best friends; that is to be expected. This, however, had crossed the line of just friendship into something neither of them were really ready to consider at the moment.

His face burns a red bright enough to match Izuku's as he quickly turns away. "I'm still mad at you," he spits out, trying to regain control of the situation that had veered off the course he had originally intended. "Stupid," he adds, just for emphasis. Then he quickly beats a hasty retreat from his friend's bedroom before he gets an idea to do something even worse – like kiss him again. He says a brief goodbye to Deku's mom before leaving and heading back to his own house.

As he walks, though, he can't get their brief kiss out of his mind.

. . .

Katsuki tries to pretend that nothing happened between them the next time he sees Izuku, though it quickly becomes clear that the other will not. The older boy is awkward around him now, barely looking at him and keeping a further distance than he used to. Katsuki hates it. But most of all, he hates himself for ruining what they had between them.

Izuku doesn't outright avoid him, but he's changed up his schedule enough that he doesn't run into Katsuki as often as he used to and it's slowly starting to get on Katsuki's nerves.

Something is clearly going on with the other boy, that much Katsuki can tell. It may not be blaringly obvious, but he knows Izuku better than even his mom so there's no hiding anything from him. He wants to ask, to talk to the other boy, but Izuku always seems to run out of things to say when they do meet – a first, in all the time they've known each other – and never hangs around long enough for Katsuki to really dig.

He's slowly going crazy, but he knows this is all his fault. He made his bed, and now he has to lie in it.

And then at the beginning of the new school year – Izuku's first in high school – it's like a switch is flipped and the older boy is back to normal, so suddenly Katsuki nearly gives himself a mental whiplash. He's seeing Izuku on a regular basis as the other walks home from school – a school he's been suspiciously quiet about, avoiding the topic when Katsuki tried to bring it up once – and when the other comes over to help him with homework, just like he did before. It's almost as if the months of awkwardness never happened.

Of course, some things are a little different and Katsuki notices each and every one, though he can't explain any of them and any time he tries to ask Izuku he's brushed off, given a vague answer, or outright lied to. It hurts, he realizes, to know Izuku is keeping something from him. But he's also afraid that if he pushes things too far they'll go back to those ten months of barely any contact and he would do anything to avoid that torture again.

So – for once – he keeps his mouth shut and hopes to hell that Izuku will tell him the truth someday.

. . .

Finally he's graduating from middle school, and after receiving his high school acceptance letter his mom predictably threw him a party. Of course the Midoriyas were invited.

"I'm so proud of my shithead of a son," his mother gushes as they sit down at dinner. She holds a glass raised to toast and Katsuki is already cringing in embarrassment. "He finally got into UA after working so damn hard. Though honestly it would've been a fucking disgrace if he hadn't, especially since he's been boasting about being the number one hero since he was a damn child." Katsuki shoots his mother a withering glare but it does nothing to diminish the proud smirk on her face.

"Congratulations, Katsuki," Inko adds, smiling proudly as if he were her own son – or son-in-law.
"UA is a brilliant school, after all." And here, Katsuki notes with confusion, she darts a brief glance over to Izuku at Katsuki's side though it returns a moment later. "I'm sure you'll excel among your peers."

"You're damn right I will," he agrees, putting the observation aside in favor of grinning at her before turning to look at the older boy beside him. "So, Deku, jealous?" he asks. He can't help but tease the older boy; it's a habit he'll never grow out of.

Izuku merely smiles, and though it seems genuine enough Katsuki can detect another emotion behind it he cannot identify. "No," he replies. "But I am proud. I know you'll be the best, Kacchan. You said you would."

Katsuki desperately tries to keep the blood from rushing to his face at Izuku's words, though judging by the quiet snort from his mother he doesn't entirely succeed. He coughs to gather himself before speaking again. "Of course I did. Just watch. I'll beat all those losers and become the number one hero."

Izuku's lips quirk in another cryptic smile and Katsuki has no idea what it could mean.