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So What If I Know You

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There’s no mark, no clock, no sound, no words— people just, somehow, know

What complicates the whole matter is that pairing— the existence of soulmates (if romantic, fanciful language is to be applied)— is not very common. Scientifically, it seems not to be able to be quantified. There’s no change in hormones, blood chemistry or synaptic connections. No physical changes either. The best way of confirming a pairing, it seems, is through the vouching of other people. Some couples may act and claim it, but a true pairing, it seems, is incontestable as judged by the consensus of family, peers and the community.

Which is why possible pairs are deemed candidates when first thought to form, usually during adolescence. Most couples only ever become pair candidates, if at all. When established in a long-term relationship, they become pair apparents, although the term is usually reserved for when the couple is legally joined and upon the birth of their first child. Once their child’s Quirk manifests and settles, and with the endorsement of a panel of teachers, mentors and other experts, the pair is finally confirmed.

All this due to the historic and much-cited Coruscant Study of Confirmed Pairings, a longitudinal study spanning 100 years of continuous research which has shown that individuals in a confirmed pairing led better, healthier lives: less risks for degenerative diseases, cancers, autoimmune dysfunction and mental illness, more financial stability, greater involvement in community and social efforts, and other such positive factors, even accounting for differences in sex, race, sociopolitical status, and even Quirks. However, the most critical of the study’s findings, and what has propelled it onto the second and third generation rounds of research, is evidence which posits that offspring from confirmed pairs manifest the strongest Quirks. 

Except, there’s always a caveat. Not all children display strong Quirks. In fact, some of the children manifest unstable, life-threatening mutations. Not to mention that some pairs are same-sex, and the Quirk enhancement that may occur between confirmed pairs does not seem to manifest with offspring of a paired individual with a surrogate or donor.

And so confirmed pairs are seen kind of strangely: as either luck or a curse, if not for the individuals, then for their children, and the relationships that they will create. On the one hand, the Coruscant Study indicates that pairing leads to an overall increase in general happiness and life satisfaction. On the other hand, The Mandalore Institute’s research into the loss of a pair half, even among pair apparents, drastically raises risks for disease and mental illness. Children who do not luck out in terms of Quirk inheritance might experience early morbidity and mortality, and even those who do may be prone to self-destructive and/or antisocial behaviors or developmental and personality issues.

And yet, popular culture has a way of biasedly portraying pairs as the height of romance. The greatest romance films of all time present the concept quite well: the framing and lighting just so, the music elevating the visuals by playing to just the right emotions. Usually there’s slow motion. Close-ups. For some reason, a focus on the pair’s hands. A particular scene from an award-winning film from the 50’s has even resulted in a lot of young couples, in their real lives, exchanging the words ‘I know you’ while putting together their hands, palm to palm, copying the main characters meeting as older pair candidates. A recognition of each other, wondrously, finally, amidst a sea of other people.

Katsuki never had this cinematic moment.




He was 4 years old, eager for another day at daycare, when a new boy joined their class. Katsuki glances up from the All Might drawing that he was showing to Osha-kun and Haru-kun and sees a small boy come into the room, stopping to stand behind Kenji-sensei’s leg. Their teacher smiles and pushes him forward, asks him to introduce himself.

Looking down, the boy says, softly. "H-hello. My name is Midoriya Izuku.” He pauses, sounds like he might want to say something more, but then finishes up with, “Nice to meet you.”

From his seat in the middle of the formation of tiny desks and chairs, Katsuki can see the new boy clutching a familiar keychain figurine that’s hanging from the corner of his yellow sling bag.

Excitement runs through him.

“Is that the limited All Might from Bespin Arcades?!”

The new boy’s whole body jerks in surprise, he finally looks up and Katsuki sees blazing, bright green eyes.




That first day, it's like Izuku is the only other kid that exists in the world. Katsuki carelessly asks Haru to move and makes Izuku sit right next to him. They talk about All Might, Izuku's old house in Tokyo, how Katsuki's dad can make tiny sparks when he rubs his hands, and how they both want to become Heroes.

Katsuki teaches Izuku the words to the song they're learning in Music. Shows him the flowers he grew from seeds a few months ago, growing tall in the garden. Makes him stand behind him when they line up to wash their hands. Eats with him, even giving him half of his hambāgu. And lays down next to Izuku after lunch, their blankets matching, with the smiling face of their idol.

Kenji-sensei seems to find it interesting. Looks kinda funny at Katsuki and how him and Izuku are suddenly so close. When his dad comes to pick him up, their teacher asks Katsuki to help the girls put away the toy boxes. When that's done, he sees his sensei talking to his dad, their expressions quite serious, often looking back at Katsuki. He'd be nervous if his dad wasn't smiling at him like always.

After a while, his dad calls him and he goes to pick up his bag. Izuku is doodling and coloring in his seat. His mom works until later and there's no one to look after Izuku even if he can walk back home by himself. Katsuki takes the banana milk leftover from his snacks from his lunch box and leaves it next to his friend's sketch book.

"Bye, Izuku!"

The green-haired boy smiles and says, "See you tomorrow, Kacchan." One day and he already earned himself a new nickname.

Walking out of the daycare, they make it down the road before his dad asks, "I see you met a new friend, eh, Kacchan?"

There's something wrong about the way it sounds, not just because he knows his dad is teasing him.

"Don't call me that! Izuku just moved with his mom from Tokyo,” he said. "Oh! I forgot to ask about his dad."

"Your teacher said you and Izuku-kun were together all day. Did you have fun?"

"Yup! He also likes All Might! He has the keychain I was telling you and Kā-san about, do you remember?" He really wanted one because the arms and legs can move and you can make different poses. "Izuku's shy and quiet but he's cool, too."

His dad has a weird smile, looking at him sort of like how Kenji-sensei did. "Yeah? When you started yochien, it took the whole year for you to be friends with Osha-kun and Haru-kun, right?"

"I guess. But Izuku's different," Katsuki answers. 

"Sō ka? I'm really curious now," his dad says. "You should introduce me tomorrow."

Katsuki makes a sound like he's part embarrassed, excited and annoyed. He doesn't need to verbally say it for his dad to understand him. "I'll just say hi!"

"If you want to, I guess it's ok. Can we go to the konbini? Kā-san said I could get chips yesterday but she didn't buy me any."

His dad continues to laugh as he swings their joined hands together, acid sweat slightly tingly in his palms.




Later, his mom comes into his room, still wearing her work clothes and Katsuki tells her about his day. Her normally loud reactions to his stories are quieter, although she giggles when he starts to sing the song. When Katsuki's done, she pets his hair and asks him, "Katsuki, do you remember what I told you? About how me and your dad are soulmates?"

As if Katsuki can forget. Those sorts of stories are everywhere in books and tv.

"Some special people are pairs. They have their closest person. The one they like the most in all the world! Like you and Tō-san."

"Well, maybe the people themselves aren’t special. But the bond they have certainly is!” When she smiles, his mom looks even younger than she already does. “Who knows, you may even find that you have one, too. Someday.”

For a 4 year-old, Katsuki is really smart. He thinks he understands his teacher and his dad. His mom seems to be the final clue.

"I already found him," he says. "Today, at daycare."

"Really? Your dad called me when you got home," his mom replies. "There's a transfer in your class, huh? You think it's him?"

"Izuku." The name is clear in his mind. So is the shy smile, happy voice and shining green eyes.

His mom sighs. 

"But you're so young to have a candidate. Your dad and I were 19, and still apparents, even now." She's saying words he doesn't understand now. "Just— don't rush, okay, Katsuki?"

Katsuki's not sure how he can be rushing, when him and Izuku just seem to have been brought together, without the two of them having anything to say or do about it.




Nothing changes until, some months later, during playtime with the other class, Katsuki's running and suddenly his sweaty palms crackle and ignite. Not like his dad's tiny sparks, but mini-explosions, loud and shocking.

He's gotten his Quirk! This is his Quirk and it’s totally cool!

The two teachers make sure the other children don’t stand too close while looking on with awe in their eyes. "Wow, Katsuki-kun! What a flashy, Quirk!"

"Yeah, a Quirk fit for a Hero!" Kenji-sensei flashes him a wide smile.

He's ran way ahead of Izuku, so a few other kids are already gathered around him as he forces more sweat and they ignite in his hands. But his red locks eyes with green in the crowd. Izuku's face has broken out in the largest, gummiest smile he's ever seen. Katsuki's sure Izuku's crying, too.

He got his Quirk. It's just a matter of time. And then him and Izuku would be on their way to being the greatest Heroes!




Another school year starts, Katsuki turns 5, and Osha-kun's light blue hair becomes like a cloud, changing depending on his moods. By summer, Izuku's birthday passes and, when they get back from break, Haru-kun can hold his breath for up to 5 minutes and then blow air stronger than anyone else in class for 1 minute straight.

Katsuki continues to play with Izuku, egging him to run more, faster, so that maybe he'll start breathing fire any day now. He's taken to leaving small bits of balled up paper on Izuku's desk, hoping to see them floating, sticking, repelling, anything, but nothing happens.

By the time he turns 6, Katsuki can make strong enough explosions that it’s a threat to him, his classmates, and even the teaching staff. Instead of staying in daycare after kindergarten classes, he's enrolled in a special school for child Quirk management. It's not exactly Quirk training, but Katsuki still feels like he's being fast-tracked through to his dream of going to a Hero school.

He tells Izuku, and his other classmates, all about it before class and during lunch, but after a while of their awe and excitement, he starts to feel a shift in their feelings towards him. He wouldn't mind it so much from Osha-kun or Haru-kun (or the others, what were their names, again? Yamanaki? Yamanashi? The one whose hair turned to leaves! Fushi..kawa? She was partnered with him for cleaning duty a few times. She can... measure weight by just looking?) but lately Izuku's eyes seem to glaze over when he talks, or else he goes on and on about a tv show or something else during lunch instead.

It bothers him so much that he tells his mom and dad. But they never experienced the same thing, and Katsuki ended up asking his trainer at his special school instead, despite how annoying it seemed.

"It's not wrong to be worrying about this at all, Katsuki-kun," Ikameshii-shishō tells him. "It makes sense for you to feel a widening gap with your friends."


A widening gap. 


"You've chosen, at a very early age, what you want to be. And you're giving everything you have." His shihō's face is calm, but he can see the determination he feels reflected in the shape of her brows, the tightening of her jaw. "You should be ready to feel this more and more."

“But, shihō. Kā-san said Izuku might be my pair candidate,” he argues, trying to say the word without tripping up. “So we should always be together. And like the same things. And go to the same school. I’m going to Yūei, so he should, too!”

“You’re too young to have a candidate, Katsuki-kun. But even if you did, would you like to fall behind, just to wait around for Izuku-kun?”

The question, if anything, distresses Katsuki even more. But he understands what his trainer is talking about. While in training, he does more exercises than in P.E., learns about historical Heroes, solves puzzles, and studies with other children with stronger Quirks. He’s always tired by the end of it, and he has more homework than anyone at kindergarten, but he’s so excited for every time he’s there learning. 

“Maybe Izuku’s not happy with me because he misses me while he’s alone in daycare,” he later tells his dad as he helps to wipe the dishes dry. “That means we should both go to training, right, Tō-san?”

He tries to bridge the gap and invites Izuku to come with him to the training school. He even asks Midoroya-san and his shihō for permission. Just for a week, like a trial run. Even if he doesn't have his Quirk yet, Izuku can still join the workouts and puzzle exercises. If he likes it, then Izuku can talk to his mom about the tuition. Katsuki can be too eager sometimes, but he asked, and he was told a single-parent (especially single mother) family can get a big discount.

"Bring extra clothes. And pack a big lunch!" he reminds Izuku. "And don't worry about a ride home, Dad will take us!"

The next day, Izuku's absent. The day after, he disappears magically before lunch. For 4 days, Katsuki's late to training by 25 minutes because he misses the bus, waiting for Izuku to join him by the school gate.

The weekend comes and Izuku never went with him even once.





He doesn't know what to say. His dad had tried to have a conversation with him every day during the week of Izuku's no-show. His dad's coming from work so his briefcase and other things are in the backseats, along with Katsuki's backpack, lunch bag, laundry bag and extra shoes. 

It's Monday, Katsuki skipped the kindergarten and his mom drove him to training school during her lunch break. It's Monday and he's already had a bad week. 

"Why didn't he come to train with me?" He's close to crying and it's making his head ache. "Did I push too much? Did I annoy him?"

He knows what his parents say. Katsuki's trying so hard. We're so proud of him! What the teachers say. He has so much potential! A natural-born talent! How his shihō treats him. One of the best I've trained. And at his age! 

There might be Osha-kun and Haru-kun, always looking up to him. Bakugō-kun's so cool! He's the best! But he knows what the other kids say, too. Bakugō's so annoying! He's so arrogant! No one really cares about his training school, why doesn't he just shut up about it already? His Quirk is only good because his parents are pairs anyway.

Did Izuku--

"Katsuki." There his dad was again. "I don't know what happened. I don't know what Izuku-kun feels. Maybe he wasn't ready? He was probably scared. Or intimidated. Do you remember that word?"

He nods, sees his dad glancing sideways at him. "Training’s your thing, but maybe it's not his. Have you talked to him?"

"I would! If he stopped hiding from me!"

"Okay, you know what? How about we visit him and you can invite him for a sleepover?"

Katsuki can't help the smile that takes over his whole face. "Can I? Really? But it's Monday! We have school tomorrow!"

His dad pats him softly in the head. "I already called your school. If he says yes, you can miss school tomorrow. But just tomorrow, ok?"

Katsuki has to remember his breathing exercises so he doesn't blow up the car in excitement.




Midoriya-san doesn't look surprised to find Katsuki at her door. In fact, she already has a bag packed and ready at the shelf by the genkan when Izuku comes out from his room.

"K-Kacchan? Mom, what—?"

Izuku's bag was already being strapped onto his shoulders. The manga at his hand ends up hovering towards Midoriya-san, while she pushes her son towards putting on his shoes.

"You and Katsuki-kun are having a sleepover, okay?" If she thinks her voice is low enough, she's wrong. Katsuki can hear very clearly. "Whatever you're fighting about, talk and make up, okay?"

"Come on. Let's go, Izuku." He bows to Midoriya-san, grabs Izuku's arm and heads down to the stairs. His dad had gone ahead. They just need to cut across the park, walk a bit and they'll end up at his house in a few minutes anyway.

Unable to help himself, he rushes to stand on the swings when they pass by. Izuku opts to sit, barely managing to get fully on top of the seat, afraid his bag will cause him to topple over like an overturned turtle.

Izuku looks like he'd rather be lanced by the swordfish-Quirked Villain they saw on tv last time than look at Katsuki, so he's surprised when the green-headed boy speaks first.

"I'm— I'm really, really sorry, Kacchan!"

He'd hoped the waterworks can start when they're alone in his room, but alone in the park works, too.

"I.. I don't— I don't have a Quirk, Kacchan," Izuku says, voice almost too soft to hear.

"What, did you think I forgot?" He really doesn’t like it when Izuku cries. "It doesn't matter anyway. You just turned 6! There's plenty of time to get it yet!"

"But what if—" sniffles "—what if I never get one?"

"There are no Heroes without a Quirk." What comes out of his mouth sounds mean, but they're true, too. Katsuki doesn't understand why Izuku would ask such a stupid question. "So you're definitely gonna have one. Since we'll both be Heroes!"

"K-Kacchan," the smaller boy hiccups. "I'm still gonna try! Even if.. even if…"

He looks at the smaller boy, his cheeks puffed, eyes red and remembers what his mom said. Izuku is his pair candidate. Chosen, made, born— whatever— perfectly for him. Remembers what his shishō said. A widening gap. You should be ready.


Izuku's hands wipe at his wet cheeks and rub his closed eyes, trying to get the crying under control. Izuku looks up at him, hopeful at the tone of his voice.

"I've chosen to be a Hero. I don't know what you want to do now but I'll be a Hero." Katsuki sounds as serious as any kindergartener (in his final year!) can be. "I'll always win and be number 1, just like All Might!"

He goes on. "I don't know what Quirk you'll have. Dunno if it'll be cool and awesome or useless and lame. But I'm gonna train! I'll work the hardest! If you slack off, I'll leave you behind in the dust!"

This is his answer to his shihō's question. He won’t be left behind. Not having Izuku by his side is painful to think about, but less painful than not achieving his dream. Less than giving up. Less than not winning.

If Izuku’s his true pair, like his mom and dad and his teachers think, if they’re meant to be together like he knows they are, then the answer should be easy for him, too.

"Even if I never get a Quirk. Even then, I’ll do my best!” Izuku doesn’t often raise his voice, so it’s funny to hear him try to match Katsuki’s own shouting. “I want to always stay at Kacchan’s side. I’ll be a Hero, too! Even if I’m Quirkless, I’m going to be the first!”

Somehow, Izuku sounds sure. Sounds like he really believes it. Sounds like he'll make it come true. Katsuki never should have doubted him.

"I'll watch you," Katsuki says. "You better keep your promise, 'Zuku!"