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Shigaraki Izuku: Best Baby Brother

Summary:

Shigaraki Izuku notices his older brother acting weird and, like a good little brother, he tries to help in any way he can. After a week of trying and failing to cheer him up, Tomura and Kurogiri leave through a portal. What was Izuku supposed to do, stay behind?

or Four-year-old Izuku follows his brother to the USJ and plants a garden.

Notes:

(See the end of the work for notes.)

Work Text:

Izuku is almost 5 years old (he’ll get his quirk soon!!) and he is similar to most 4-year-olds. He likes playing with his pet, reading with his dad, watching his brother play all his video games, and he likes making everyone in his life happy.

Izuku is also very different from kids his age. Like how his dad tells him about society's flaws and how to efficiently crumble civilizations or how he likes to watch the doctor create funny creatures called Nomu with tons of different quirks. He, however, doesn’t know his life is somewhat odd as it is the only life he knows but that’s not a bad thing. Izuku loves his life and his family and they love him back even more.

Despite their love, Izuku's family is always very busy. His dad usually has dozens of meetings and tests that need to be done but that just means he gets to spend lots of time with his brother and uncle. Since he gets to spend so much time with his big brother, Izuku has gotten really good at knowing how the older boy felt. Usually, that feeling was some kind of upset but that never stopped Izuku ‘cause he was the best little brother so he always tries to help.

When Tomura was mad at his games Izuku liked to sit with him and help with the puzzles (sometimes he even got to play! But not too often ‘cause he wasn’t very good but daddy says it’s okay cause he doesn’t have to be good at everything and Izuku’s already really smart). When his older brother sees a hero on tv and scratches his neck a lot Izuku gets him a washcloth and band-aids to make him feel better and when he wants to talk about heroes Izuku always listens cause Izuku really likes heroes ‘cept when they talk about heroes, Tomura usually says mean things cause he doesn’t like them much but he also helps Izuku understand why (and he does understand but he still loves how heroes help people even if some of them are bad or mean).

All that to say, Izuku knows his brother very well so when the blue-haired man starts pacing and scratching and muttering about heroes under his breath all the time Izuku knows something is wrong but he doesn’t know what exactly… so he just tries every fix. He brings the older boy snacks and plenty of water cause sometimes when he gets really upset Tomura forgets to eat. He brings his brother band-aids for his bleeding neck and lotion so it stops itching (and lollipops for when he’s all fixed up). He tries a bunch of other stuff too. He tries to make his brother laugh or play video games or he helps clean when Tomura throws things around in his stressed state but nothing works.

After a week of trying it wears down on the little white-haired boy but he won’t stop until his older brother is better. This means when he sees Uncle ‘Giri open a portal and half his family step inside Izuku just has to follow.

 

The plan had been perfect. Over the last few weeks he’d amassed an army of low-level NPCs. They were only supposed to be cannon fodder so their skill and quirks didn’t matter, just that there was enough of them to overwhelm the enemy, which there was. Currently, he had about a dozen NPCs in each zone, all of which should be ambushing the unsuspecting hero students by now while a few dozen more were keeping Eraserhead (Eraserhead!!) occupied. His right-hand man, Kurogiri, was incapacitating the other pro-hero present which leads to where the plan and reality alter. There are only two pro-heroes present and neither of them is their target.

The man of the hour, the number one hero and symbol of peace, All Might appeared to be a no-show. According to the schedule he’d swiped only days before, the man should be here but alas he’s not, not yet at least. With his secret weapon at his side, Tomura holds out hope that causing enough damage to the facility and students will draw the man out. In the meantime, however, he takes his frustrations out on his neck. A habit he knows isn’t healthy thanks to the constant reminders of-

“Tomra you’re hurting yourself.” His adoptive brother's voice rings through his head, surely a Pavlov effect from how often the literal toddler scolded him… but it didn’t sound like a voice in his head, it sounded more like it came from right beside him. His fear is only confirmed by a light tugging of his pants and the same youthful voice whining this time. “Tomraaa you gotta stop scratching.”

Slowly the violent and mentally unstable villain turns his head and looks down, blood-red eyes meeting a sea of green. “Son of a b-“ the young adult cuts himself off in the presence of the child, Sensei always emphasized he doesn’t want his son using such childish and vulgar language. Even if Tomura is fine with torture, murder, and human experimentation, cursing in front of his pure 4-year-old brother is a line he will never cross. So instead he just gets to the point, “Izuku what are you doing here?” he also never snaps at the boy but right now the question is sharp because Tomura is literally here to murder at least one pro-hero—but potentially up to three—and quite possibly 20 hero students. His baby brother should be at home taking a nap right now.

“I wanted to help!” the child chirps, a wide smile pushing up freckled-covered cheeks and hiding deep green eyes with the force. Tomura just stares, dumbfounded for a moment, and stays that way as the boy elaborates. “You’ve been really upset all the time and I kept trying to make you feel better but it never helped. Then you were even more upset and leaving so I had to come.”

If he didn’t already have father’s hand acting as a mask he’d be dragging his own hand down his face in exasperation so instead, he opts to sigh, deeply. “Your logic is flawed, it's dangerous for someone at such a low level to be here.”

The toddler points a chubby hand towards his waves of cannon fodder fighting Eraserhead and innocently asks, “But aren’t they low leveled too?”

While technically correct he wouldn’t let a four-year-old win this argument. “They are all expendable NPCs thus your point is invalid.” Izuku looks thoroughly unimpressed so the villain decides to go with a low blow, the boy’s compassion. “Plus Sensei would kill me if you were injured so you have to go.”

“Nuh-uh! I wouldn’t let him!”

Tomura raises an incredulous eyebrow, “Oh yeah? And what would you do pipsqueak?”

The small white-haired boy’s smile drops along with his eyebrows as the boy attempts an intimidating expression that he pairs with pumping his fist into the air. “I’d punch him right in the face!”

“Ineffective. He lacks all weak points that make the face an efficient target.”

His pseudo brothers face contorts as he presumably attempts to think up a counter and when the boy looks down and kicks his bright red boot against the concrete Tomura almost thinks he’s won, almost. “Well…” the boy slowly starts, “Uncle ‘Giri left so you can’t send me back.”

The handheld man whips his head to the right just to find empty space. Fuck. He’d been so distracted with the kid that he forgot all about their actual plans. Kurogiri has been at the entrance for a few minutes and may not return for even longer.

“That’s a bad word, Tomra,” the small boy condemns and shit he said that out loud. Okay, new solution. Sensei has been teaching him for years how to plan for unexpected changes, he can do this.

Pulling plans out of his ass, Tomura speaks, “Do you want to help me analyze Eraserhead’s quirk?”

He really should have expected the squeal that always follows the word ‘quirk’ around the boy along with the chant of, “Yes, yes, yes!”

Fondly, the blue-haired man (-child) rolls his eyes at the antics of his brother and kneels to the green kid's level. “Geez, calm down short stack. You don’t want to draw attention to yourself in a battle like this. We are here to observe until it’s my time to engage the enemy.”

Izuku looks up with stary green eyes, “When will it be my time to en-gage the enemy?”

“Level up first. Right now you are just a glitch in the system, entering a level you are not yet prepared for so you will do as I say until you level up sufficiently. Got it?”

He nods seriously. “Yes, Tomra.”

Tomura nods back and directs their attention back to the fight before them. “Good, now tell me what you see about Eraserhead’s quirk.”

His kid brother hums in concentration while staring, studying the hero with more intensity than a normal four-year-old could. “Eraserhead has a… emitter quirk cause he doesn’t have any mut-tat-ions and his body isn’t changing like a transf- transfor-”

“Transformation.”

“Mhm! It's a mental quirk ‘cause it's gotta do with his brain and that’s what makes his scarf and hair float but that's not his quirk. The other NPCs keep messing up their quirk attacks so… it must be like daddy’s!”

“Close, he can erase emitter and transformation quirks as long as he can see a person. So you saw his tell but can you tell me anything else about the telekinetic field?”

“What makes everything float?” Tomura wordlessly confirms knowing too much talking will interrupt Izuku’s analysis zone. “I think that it’s a side effect that lets him use his quirk better. The tele-ki-netic field keeps stuff from getting in the way of his eyes and probably keeps dust out of his eyes too.”

“While those are good observations that's not what I was talking about. Every time he blinks his quirk stops, just for a moment so his hair falls, the scarf too although since its support gear it doesn’t fully rely on the field. The more he uses his quirk the shorter he can use it the next time he opens his eyes. This will allow an opening for me to take him out of the game and from the looks of it that opening will be soon.”

Izuku nods along to his observations, staring at the hero so Tomura assumes he’s looking for the pattern in quirk use. When he finishes his mini-rant the boy looks up at him with sparkling eyes, must be a trick of the lights, he thinks. “You're super smart Tomra,” the green-eyed boy says in obvious awe and admiration.

Tomura pushes his brother's face away, one finger lifted, and feels glad he has a mask on. “Yeah, whatever tiny.” He looks back to the fight and notices Eraserhead’s quirk recovery time is just where he wants it. Taking a deep breath he turns back to his brother. “Alright I gotta make my first appearance now so…” He turns away from Izuku in favor of the ground and decays a small patch of the concrete below them, “your new objective is to make me something cool for when I get back.”

Izuku tries to put on a serious expression but his excitement over being ‘helpful’ shows in his energetic bouncing. “Okay! I’m gonna pass this level and get tons of XP!”

The villain huffs at his decidedly not adorable brother and puts on his game face. He has a job to do.

 

Izuku was having tons of fun. He finally got to help his big brother with quirk analysis and Izuku is really good at quirk analysis. He even has a few quirks right now although they were all presents from his dad.

When he was born his dad gave him a regeneration quirk. The quirk allows him to heal most injuries in just a few minutes and it’s harder for him to get sick. His second one is a minor intelligence quirk. At first, his dad didn’t want to give it to him cause he said Izuku was plenty smart already but Izuku begged and begged because he always wanted to read but Dad, Tomura, and ‘Giri were usually too busy to read to him that often so after many, and, in Izuku’s opinion, compelling arguments the man relented. Finally, Izuku always has at least one other quirk to play with, experiment with, and study. Sometimes this quirk helps him learn something his dad wants to teach him but often times it’s given to Izuku because it relates to a subject he’s already obsessed with.

Right now this third quirk is plant creation and he has it because he’d been reading about all kinds of flora and the processes that keep them alive like pho-to-synth-is-is. After dozens of plant-related questions his dad gave him the quirk so he could find the answers to some of them himself. Plant creation has a bunch of different requirements like he needs to have an image of what plant he wants to create in his mind, then he needs the necessary water, sunlight, and nutrients that the plant would need to thrive but once those requirements are filled he can create anything. After a bit of trial and error, Izuku has gotten the hang of it and now the bar is filled with greenery.

Like he always does, Izuku did consider his family while creating his jungle so he asked everyone what their favorite plants, flowers, and trees were. His dad and uncle gave the best answers, lots of things they liked but also some unique and challenging ones. Tomura, despite how he tried to seem interested, had no real suggestions (Izuku had tried creating the plants from video games as his brother had suggested but once they destroyed the terrifying evidence of that experiment, the pair swore never to do it again). All that to say Izuku has no idea what Tomura would like but that just means he gets to be creative with his garden.

It only takes a minute for Izuku to decide that he’ll make something meaningful using what he remembers from his Hanakotoba book, which thanks to his intelligence-enhancing quirk is quite a bit.

Inspired, he puts his hands into the revealed dirt and imagines a flower. Drawing nutrients and water from the soil and energy from the sun shining through the glass dome, a small green sprout peeks out and begins to grow before his eyes. He concentrates until vibrant pink petals form a full-grown flower. He repeats the process until he has a small patch of carnations, carnations that symbolize his love for his older brother. Then, he decides to repeat the process, this time with a few yellow poppies for success and edelweiss for courage, both things he wishes for his brother.

After this, he has quite a bit of space left but a limited amount of water and needed nutrients to supply his creation’s growth so he decides to grow a few more flowers. He creates three flowers with large orange petals surrounding a long style and filaments. These orange lilies were meant to show his older brother’s hatred because while Izuku knows Tomura loves him he also knows the taller boy loathes All Might (he’s not supposed to say this but Izuku actually loves the number one hero although he doesn’t mind that his family doesn’t).

Next, he decides to fill in the extra space with some small greenery which doesn't take up nearly as much energy or resources but even after all that, his little garden still feels lacking. He has a lot of complementing warm-colored flowers, some cool white that pops but doesn’t clash, and lots of green closer to the ground that fills the space. It feels incomplete but adding anything else might… actually there is one flower that would look really good with his pink carnations, his yellow poppies, and his orange lilies. Izuku dirties his hands once more and concentrates on growing his last flower but he is so focused he doesn’t even take notice of the new player entering the game.

With what he has left he can only make one more flower but that’s alright, it doesn’t need to be much to complete his objective and level up. In the middle of his garden a bright red flower blooms as the piece de resistance, if only he could remember what it symbolized.

Taking a step back to admire his work Izuku has the beginnings of a smile growing on his face, that is until the boy is thrown back from his garden by the quick and seemingly never-ending punches being exchanged between All Might and the Nomu. He barely spares a glance towards his favorite hero, instead only thinking of his objective. Looking back at his project Izuku’s eyes start to wet with fat tears. His flowers… they’re ruined, all at the very least lay flat on the unforgiving ground while most are being thrown around the concrete padding. That was his objective, how is he supposed to level up now?

Distracted by his questions and emotions Izuku hadn’t even realized what stopped him from his fall until a loud voice calls from right next to his ear. “Don’t worry kid, we’ll get you away from these meanies.”

Izuku looks up to see a big, sharp smile just in time for two strong arms to wrap around his waist. He does not like that so Izuku decides to do what toddlers do best, he screams.


When they get back to the main plaza it's a mess. The dozens of villains Hobo-sensei had been fighting are all out cold, and a handful looked a bit more than just unconscious. On the road here they heard the door slam open and the number one hero announce his arrival. Now the man seems to be dropping off a bleeding Aizawa by the front doors. He shoots back down, likely with the intention to end it once and for all but is actually stopped by a bonafide monster. A hulking mass of muscle with a sharp beak and bulging brain, it barely looked human.

All Might, well known as the strongest man alive, begins trading even blows with the thing which causes shockwaves making even Katsuki stumble back a few steps. His classmate seems to be having better luck… is that a fucking child? The high-pitched screaming answers his question.

“God will you shut that thing up?” he screams over the fight but it seems that wasn’t enough to grab his shitty-haired classmate’s attention, however, someone did notice them.

“You!” they screech, “Get your hands off Izuku.”

Both teens snap their heads up to see the villain covered in disembodied hands sprint towards them like some eldritch horror. Shitty Hair turns to him and holds out the kid, “Get him out of here!”

“You don’t tell me what to fucking do,” he snaps but still grabs the kid and, with the small child held under one arm, he launches them into the air with his quirk. His balance is off and he can’t get very high with half his usual power plus the extra weight but he manages.

They’re almost to the stairs when his forearm begins to tickle before blooming in excruciating pain. He almost drops the brat but corrects his course so that they both land rather roughly a good distance from his original goal. He can hear the madman screaming from behind him but before he can continue to book it he hears his name called from his left. Also on their way to the stairs are Frog Face, Grape Fuck, and Eyebags. Perfect. He lets them catch up to him and unceremoniously drops the twerp in Eyebags’ arms.

The purple-haired boy holds the writhing toddler at arm's length and looks back at Katsuki. “What the hell am I supposed to do with him?”

“I don’t fucking know!” Right now he’s a bit more worried about the patch of grass replacing a large portion of skin on his arm. Disgusting.

“Here, ribbit, I’ll take him,” their part-frog classmate offers, hands already extended for a trade-off. Eyebags gladly hands off the child to their seemingly logical classmate but seems just as surprised as Katsuki is when the short girl addresses the crying boy. “Do you want to go home?”

The boy quiets down to a sniffle, “I want Tomra,” he whines pitifully.

Frog Face resolutely nods her head in understanding. She turns towards the pissed-off villain and copies the pose her classmate had just been in, offering the toddler up. The man stops his attack just centimeters away from her and before he could do anything Frog Face spoke. “You love each other. A family like that shouldn’t be broken up just because you’re a villain.”

After a quick calculated look the man, astutely aware of his hands, takes the kid and quickly retreats but not without throwing a quiet and cautious, “Thank you,” over his shoulder.

The red-eyed man meets up with his ghostly associate and exchanges a few words that end in a familiar rift being opened in a previously empty space. Then, without even seeing how the fight between All Might and the monster goes, the villains and brat leave with only a few parting words.

 

Sakata Yumi never liked nature, she hated the forests and fields that surrounded her childhood home. She hated spending her teenage years working in those fields because there was no other job available in her rural town for a 16-year-old but above all else, she hated that her mother liked to garden for fun. Why, in a life surrounded by greenery, would you have a hobby of growing more?

Despite her hatred, Yumi was somehow the only one ever available to listen to her mother drone on about her dumb flowers and their stupid meanings. That woman could go on for hours about the dullest things and in that time Yumi, regrettably, picked up a bit.

The second she graduated high school she was off to the city and away from the town that suffocated her from birth. She enrolled in the police academy, did well in her courses, and graduated, immediately moving on to a decent job. While not as exciting as being a hero she still felt like she was doing good and no matter what knew she’d never have to think about sitting in the hot sun, sweat dripping down her neck as she watched her mother dig her hands into dry dirt, trying to create new life. Never did she think that flowers would come up in police work but as she stands in the middle of an abandoned battlefield she doesn’t know if she appreciates or hates the knowledge forced upon her.

Bright yellow success.

Sharp orange hatred.

Pure white power.

Blood red death

Destroyed flowers and scattered petals make a promise.

“We’ll be back.”

Notes:

Carnations symbolize love or fascination, yellow poppies symbolize success, edelweiss symbolize courage or power, tiger lilies symbolize hate or revenge, and red spider lilies (the flower Izuku couldn’t remember the meaning of) symbolize mourning or death.

Thanks for reading! Comments, kudos, and criticism are appreciated.

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