Oh man. So this started as a joke-prompt that turned into something serious and that's basically the story of my life. *snort* And just so it' s up front: End game is BakuDeku, but he is dating an OC for a while, so I figured I should give you a head's up. Our lovely OC is named Daiki because that's the name of Izuku's voice actor & it's fairly common. If you're curious why it's an OC, it's because I hate breaking up couples in fanfics when someone might have shipped the original couple. :D

Anyway, it'll probably be short with two to three parts. I was going to do it all in one go, but decided to split it up when the story refused to cooperate. Enjoy!

Chapter 1

"Bro! Who's that?" Kirishima asked, voice bright and surprised.

Izuku looked up from searching his backpack for that last pen he knew he had brought with him. From the other side of the small diner booth, Uraraka and Iida's eyes were already glued to Bakugou's usual table. Izuku spotted Kirishima with his hands on his hips, grinning at Kacchan and someone new next to his side as they entered the small diner.

The new boy was fair looking with soft, brown eyes and straight, black hair styled with a long fringe that framed his face. He was about Kacchan's height, only a fraction shorter, and had a warmth about him that made him seem like an easy guy to like—much like Kirishima but calmer. The collared shirt and neat blue jeans only added to the image of friendliness.

He was an oddly appropriate foil to Kacchan's harshness.

Kirishima scrunched his nose as he grinned and laughed brightly. "Are you going to introduce him or what?"

"Yeah, Katsuki," new boy said. He took Kacchan's hand and laced their fingers together. Izuku sat up higher in his seat. The new boy squeezed Kacchan's hand with a teasing smirk and leaned on Kacchan's arm. "Introduce me."

"This is Daiki," Kacchan said, face flushing red as the new boy curled his arm so that their bodies were flush. Kacchan swayed their linked hands a fraction, before squeezing it back. "My boyfriend."

Izuku dropped his book, but the clatter went unnoticed with the shock of everyone else who'd chosen to crash at the diner for the impromptu study session.

"Nice to meet you," Kirishima said, oblivious to the curious staring that had engulfed the rest of the room and had centered on his conversation with Kacchan and Daiki. "I guess this explains where Bakugou's been running off to so fast every day after school."

"Guilty," Daiki said, still leaning on Kacchan's arm. "I've been stealing his free time rather liberally. I'd apologize, but I'm not really sorry about it."

Kacchan snorted and shoved Daiki playfully in the side with his elbow, but didn't let go of his hand.

Izuku had noticed Kacchan disappeared fairly often these past two months, but Izuku always assumed he was just out training.

Not. Not whatever this was.

"So how'd you two meet?" Kirishima asked. "You're not a U.A. Student, right?"

"No, I go to a local high school down the street," Daiki said. He tilted his head to the side, knocking his bangs across his cheek, revealing a slight curl to the strands. "Katsuki and I ran into each other while he was jogging—literally. He knocked over all the garden pots I was carrying and helped me clean them up. I thought he was cute, asked for his number, and well," Daiki bit his lip. "The rest is kind of obvious."

"That sounds adorable," Kirishima said, leaning his chin on his hand as Ashido cooed next to him with a wide grin. "Though I'm surprised Bakugou ran into you. He's usually got better reflexes than that."

Kacchan huffed and flushed a deep red, looking off to the side.

Daiki raised a hand to the side of his cheek and whispered, "He said later he was too distracted by how pretty I was to pay attention to where he was going."

Kirishima burst out laughing alongside Daiki and Kacchan shoved the two of them while sputtering out exclamations of denial, proven false by the red still on his cheeks.

Izuku felt a weird, squirming sensation in his gut and discretely dismissed himself from the table to head home before he could linger too long on what that meant.

Daiki had become a common fixture around Kacchan whenever they weren't in school. To say they were glued at the hip was an understatement and people had started to refer to them as a couple nearly all the time.

Everyone loved Daiki. He was smart, kind, and had a wicked sense of humor that made even Iida chuckle. His grades, however, were on par with Kaminari's which gave him enough of a character flaw to keep him from being too perfect. Plus, anyone who could turn Kacchan into a softer person just by being around had been labeled a miracle worker in their books. Sure, Kacchan still had his fiery personality and short temper, but it quickly fizzled out with a touch to the hand or kiss on the cheek from Daiki.

It reminded Izuku of when Kacchan's mother would soften and coo whenever Kacchan's father did something romantic or kissed her on the cheek.

Kacchan and Daiki were positively domestic and adorable and Izuku had never wanted to send a Detroit Smash straight into someone's face more in his life.

(He really didn't know where this ugliness was coming from, but it was becoming a concern.)

Izuku concentrated on his homework as he sat at the coffee table, attempting to ignore the happy couple behind him on the couch.

Yaoyorozu had started having study sessions at her house every weekend when the diner complained of their rowdiness, and the entire class had been invited to come since there was more than enough room. Every session ended up with one or two people studying while everyone else hung out, which was fine, but eventually the invitation had been extended to Kacchan's boyfriend as well and that's when it all went south.

Izuku grew tense as Daiki helped himself to a seat in Kacchan's lap behind him, despite there being an open seat on the spacious couch. Kirishima and Ashido sat on Kacchan's opposite side, flipping through the television and not even blinking at the public display of affection between Daiki and Kacchan.

They were always that cuddly and it ate away at Izuku's soul like acid dissolving everything in its path. He focused on the numbers of his math homework, but ultimately failed.

Every brush of Daiki's long fingers in Kacchan's fluffy hair felt like a glaring beacon attempting to capture all of Izuku's attention. Despite his best efforts, it was hard not to watch the two of them from the corner of his eye: He saw the way Daiki fit into Kacchan's side, slender and tucked neatly under Kacchan's toned arm. Izuku noticed the way their breathing had synced; twin chests moving up and down together. Daiki tucked both his legs in-between Kacchan's thighs, gently rested his his fingers along Kacchan's belt line and tested every inch of Izuku's willpower to not walk over and rip them apart.

(He really needed to talk about these intrusive thoughts with someone before they got out of hand.)

"Hey, Daiki," Mineta said, walking into the main room from the kitchen with a bowl of snacks in his hand. Sero scoffed behind him and flushed red, hissing, "Don't!" under his breath. Mineta continued on, pouting. "Settle a bet: Is your Quirk the ability to calm people down or something else? Because I think it's the first one. Bakugou's never been turned by a pretty face before, so this animal tamer thing you've got going on has got to be Quirk related."

"I am so sorry," Sero said, covering his face and shrinking under Kacchan's glare. "We were joking around and he took it too seriously."

Daiki laughed and waved it off. He ruffled Kacchan's hair, immediately calming him down and Izuku started to wonder if Mineta had called it. A Quirk like that would explain so much, though it would also cause some concern if it had been abused to tame Kacchan. Daiki's smile softened, amused at Mineta's antics. "It's okay. No harm in asking, but I don't have a calming Quirk."

"What is your Quirk, anyway?" Kirishima asked, looking up from the Television. "I don't think you ever said."

"Oh, that's because I don't have one," Daiki said. Izuku looked up from his homework, eyes widening. His pen slipped out of his hand and clattered on the table. Daiki shrugged with a sheepish expression and bit the tip of his finger. "I'm Quirkless."

"And Kacchan still likes you?" Izuku blurted, louder than he'd intended. His brain connected to his mouth without permission, finishing the thought: "He doesn't think you're a Quirkless loser?"

Izuku regretted the comment immediately, but too many flashbacks of middle school assaulted his brain to let him access common sense.

It came back fast enough when Izuku realized Daiki looked like he'd been slapped and everyone had turned toward Izuku with varying expressions of horror and confusion. Only Kacchan avoided looking at him, eyes focused on the coffee table and Izuku's school work.

"Dude," Kirishima said, mouth dropping. He looked like a kicked puppy, empathetic to the end. "Midoriya. That was harsh, man."

"That came out really wrong," Izuku said. He sucked in a breath and swallowed, holding his hands up. Izuku's pulse quickened and his brain struggled to come up with an answer that would be acceptable. "I mean. I just."

Izuku had no way to explain himself without outing Kacchan's bullying in middle school and ruining his relationship with Daiki or admitting that Izuku used to be Quirkless—neither of which he could do.

"I'm sorry," Izuku said, sinking into the floor and leaning forward onto the coffee table. He rubbed the back of his neck and moved his other hand back and forth on his thigh, not sure what else he could say. "That just…came out wrong."

"Ah, it's okay," Daiki said. His smile didn't quite come back but he definitely looked hurt. He squeezed Kacchan a little closer with a shrug. "I'm used to it. You aren't the first to think that I'm a loser for not having a Quirk."

Izuku shook his head and stood up, arms waving. "I don't! I mean. I don't think that at all! I just was surprised and—"

He cut himself off at the silent glares sent his way, and the concern on Iida and Uraraka's faces. Yaoyorozu and Todoroki looked disappointed, and even Mineta had a serious expression on his face. Izuku shrunk in on himself and looked to the side. "I'll just go home now."

Izuku grabbed his things and hurried out of the common room, ignoring the people who called after him and hating that he was still more upset about Kacchan's arm tightening around Daiki's waist than he was for the unthoughtful slip of the tongue.

"Oi, Deku." Kacchan said, banging on the back of Izuku's door. He didn't sound angry, but the heavy knocking demanded entry. "Open up."

Izuku opened his bedroom door and faced the inevitable. "Hey, Kacchan."

"Your mom let me in," Kacchan said, explaining his presence in Izuku's home. He pushed his way into the small bedroom and kicked the door closed behind him with his heel. He paused for a minute with his hands in his pockets and shifted on his other leg. "I told Daiki you're an awkward little shit, so he's cool about the 'Quirkless Loser' comment from yesterday."

"I'm still sorry I blurted that out," Izuku said, noting that Kacchan had yet to look at him directly. Instead, he seemed very interested in the All Might figurines on Izuku's desk. Kacchan poked it in the head, titling it to the side while Izuku gathered his thoughts. "I was just sort of shocked because you're you and I never thought you'd date someone without a Quirk after you gave me such a hard time for all those years."

It's why Izuku had given up on even trying to ask Kacchan out when they were younger, and then later when he got a Quirk it felt too awkward to confirm Kacchan's shallowness by seeing if he'd say 'yes' now that Izuku had a Quirk.

He'd worked very hard at denying that he had a crush on Kacchan and Daiki had thrown that all out of the window and now Izuku found himself plagued with "What If" scenarios.

"Besides," Izuku said, rushing to add it in before Kacchan could talk or his own thoughts could get too carried away. "If I told everyone about you, I'd have to explain that I used to be Quirkless and I can't do that without explaining how I got a Quirk and I still can't tell anyone about that—I'm still sorry I can't tell you by the way—and then—"

"Whatever," Kacchan said, cutting off Izuku's ramble. He leaned on the bedroom door, brows scrunched together, almost concerned as his mouth itched to form a new sentence that didn't quite want to come out.

Izuku took a guess at what was eating at him: "I'm not going to tell him, Kacchan."

"Excuse me?" Kacchan asked, glaring.

"That's why you're really here, right?" Izuku asked. He took a few steps back and sat on his bed, pulling his knees up. "You don't want me to tell Daiki about middle school, right?"

"Like you would," Kacchan said, muttering under his breath. He scratched the back of his hair, digging into his scalp. He dropped his hand and huffed. "I told Daiki I'd let you know he wasn't mad so it wasn't awkward next time you saw each other, so that's what I did and now I'm done."

"Kacchan, wait!" Izuku shouted, sitting up and dropping his feet back to the floor.

"What, loser?" Kacchan asked.

"Do you really like this guy? Like, seriously?" Izuku asked, almost hesitant. He rubbed his arm and pressed his lips together. "Quirk thing aside, you've never really been interested in that sort of thing. Dating, I mean."

"Why do you care?" Kacchan asked.

Maybe Izuku wanted to know if Kacchan was just in it for the make out sessions with a pretty face, to let off some steam, or if Kacchan really was thinking long term getting married dating.

The first one Izuku could live with.

The second, he was starting to realize might cause some problems.

"Just curious," Izuku said. He gripped his sleeve and looked at the floor. "I've known you my entire life and this feels like it came out of the blue."

Kacchan stared at Izuku and rubbed the side of his nose. After an awkward two minutes he bit his lip and shrugged, sounding downright flustered—which was weird to hear coming from the usually confident Kacchan. "I think I do. Like him, I mean. Probably. I don't know. We've only been dating like two months, so who knows?"

Two months too long.

(Izuku mentally hit himself. Not the time. It was not the time for that.)

"That's true. And dating's supposed to be fun, right? No need to make it so serious," Izuku said. He rubbed his arm and changed the subject before Kacchan could think too hard about his feelings for Daiki. "Anyway, I'm glad he's not mad. And I am sorry I said what I did. I know how that feels to hear."

"Yeah," Kacchan said. He swallowed and opened Izuku's door. "I'll see you at school tomorrow."

"Bye, Kacchan."

Izuku waved as Kacchan left, falling back onto his bed. He covered his eyes and breathed in as he calmed down before going back to his homework.

That night, his dreams were filled with Kacchan and Daiki getting married.

He probably should have felt worse that each dream ended with Izuku crashing the wedding and stealing Kacchan away like a Villain.