#i have a whole list of things kats and eri would do toghether to cause mayhem

[anotherhellchild]

📂? 🥰😃💞!

:DD 

Okay! Katsuki and Eri friendship / sibling relationship? Here we gooooooo!!

Everyone was super excited when it was announced that Eri would be coming to live on campus, class 1a was so hyped for the girl and it was all just very thrilling. Of course, it took a while for Eri to adjust and get acquainted with everyone and everything. It was all just a bit overwhelming and scary at first but now, Aizawa can easily say that the little girl has found her place in UA. She fits perfectly in their weird, chaotic family.

Not that Aizawa was expecting any less.

What nobody was expected though, was the way Eri became attached to a certain angry and explosive blond. 

Katsuki and Eri haven't known each other all that long. But they’ve somehow managed to get to the point where they’re basically siblings. People who don’t know them personally would actually probably not even think twice about it if you told them that that were the case. They’d take one look at the dynamic between the two plus their shared red eyes and light coloured hair and they’d be sold.

Anyway, whenever Eri and Katsuki meet, it’s somehow both mesmerizing and terrifying at the same time. Eri likes to follow Katsuki around and -by some miracle- Katsuki doesn’t seem to mind. It’s almost even as if… as if Katsuki likes it. They may not realize it, but the two definitely look up to each other. Eri watches Katsuki like he’s a shining star and Katsuki watches Eri with such a fond/ proud gaze. It’s mesmerizing.

And it’s terrifying because together, the two become an absolute menace. They bring each other's hellion sides out and you’d think that isn’t possible because Eri’s so sweet and Katsuki’s already a hellion, but no. Together, Katsuki and Eri could destroy the entire campus and laugh about it and there’s absolutely nothing anybody could do to stop them.

It’s horrifying.

The first time the two properly hung out, Eri came back to Aizawa with beautifully braided hair, a knife, slingshot, at least three holes in her clothes and a lot of dirt, just dirt. The pair’d been gone for five hours without telling anybody where they were and Aizawa swears to god he was prepared to straight up commit murder before they appeared, unharmed and totally safe. 

Ever since then, Katsuki and Eri need a responsible third person around if they want to hang out or go somewhere (Todoroki and Hawks are NOT allowed to be the third person btw).

In any case, Katsuki, Todoroki and Shinso happen to be the only ones in the dorms today. Katsuki and Todoroki are on house arrest because of Reasons (injuries/ overworking themselves. idk) and Shinso’s there because he’s already learned whatever Aizawa’s teaching the rest of the class in his extra lessons and Aizawa needed someone to babysit the other two. It’s around twelve o’clock when Eri enters the dorms, Mirio drops her off because he has Stuff he needs to do and the four of them end up alone.

Somewhere on campus, Aizawa feels this random shiver going down his spine.

Things start off pretty calm, the demon spawn kids make snacks, play games and have some intense rounds of hide and seek. Maybe a chair is almost broken and maybe they’re all just praying nobody ever sits on the damn thing again, but it’s fine. “Dun fucking worry bout it eyebags! We used super glue so we’re all good.” Nothing’s on fire and nobody’s hurt so they’re cool. 

They do decide it’ll be best to stop playing hide and seek after the small uhh… mishap with the chair though. After about five minutes of contemplating what to do next, Katsuki comes with the fabulous idea to create a mattress slide.

“What’s a mattress slide?” Eri asks whilst Todoroki gives Katsuki a confused look.

“Oh fuck. You guys seriously don’t know?” The blond's eyes are wide, though he’s honestly not that surprised. “Oh shit, okay. This is going to be fucking epic!” Katsuki’s face gains a manic grin. 

Shinso’s already regretting all his life choices.

The four of them set out on a mission. All twelve spare dormitories get broken into and every single mattress is gathered and placed somewhere on the boy’s side stairs. Katsuki dictates everyone around and Eri is the head of Placement because she can’t do any of the heavy lifting. Shinso, Todoroki and Katsuki’s mattresses get ripped off their beds too and in the end, their mattress slide starts at the top (fourth) floor and ends all the way down at ground level.

It’s pretty fucking impressive if you ask Katsuki. He used to do this all the time whenever his parents left for a while. Back then, he just had two mattresses to work with though. One (his parent’s) served as a buffer at the bottom of the stairs and the other (his) was to slide down. It was definitely not safe.

This is way better.

When all four kids stand proud and tall at the top of the stairs, it’s unanimous that Eri should be the first to go down.

“Go ahead Eri. We worked hard for this, you get the honour of going down first.” Shinso says.

The glint in the little girl's eyes immediately intensifies, smile wide and body buzzing with anticipation. Large red eyes look at the slightly unstable sight of crookedly layed mattresses and without announcement, little legs leap. Eri’s a giggling mess as she rolls down the magnificently created mess and the three teen boys do not hesitate to jump after her.

It’s safe to say that the following hour or so is a complete chaotic catastrophe. And maybe that’s because there isn’t a lot of architectural intelligence between the four of them, maybe it’s because of the multiple times a head banged against a wall, or perhaps the decision to play tag on the stairs wasn’t the best, but either way, they have a lot of fun.

Maybe, when Aizawa bursts in just as all four are sprawled out over and on top of eachother at the bottom of the stairs, laughing like kids should be laughing (in a way Aizawa’s never seen before), maybe that’s why the teacher decides to let this catastrophe slide (haha get it, slide) just this once.