DISCLAIMER- I own nothing!

A/N- You don't have to have read my other stories. This isn't a cross-over in any way, so no worries there. Also, all of my OC's are only SI's in their personalities, not their backgrounds.

X

….

When I wrote my first Naruto fanfic, a sweet one about reincarnation and trolling ninja's whilst safely tucked away in my patisserie…that wasn't an invitation, Universe…!

Maybe I should explain a bit.

I was 20-year-old History student at Uni and had two much older sisters. Who were also historians. And had already written books and been recognised as stupidly smart.

You see the issue? Anything I did, they'd already done five years beforehand and probably to a better standard. We were all incredibly close and I was in no way angry or resentful but…it did get a bit draining, being the baby. My response? Becoming a fanfic writer/reader.

I'll grant you, it wasn't the most conventional way to strike out from being the same as my siblings but it was a breath of fresh air.

I'd never really written much, my old fics rather shitty and my new ones were only just starting to form. But I sure as fuck read a lot. I was still wading through my degree full steam ahead, but the fics were a nice way to let loose a bit.

Nothing got rid of tension than some funny fandom memes on Tumblr.

I'd started off with the basic mainstream ones like Naruto and Harry Potter but, the more I read, the more I stumbled across. Things like Full Metal Alchemist, Boku no Hero Academia, HunterXHunter and Bungou's Stray Dogs, just to mention a few favourites.

My dive into Rare Pair Hell was both glorious and inevitable.

I accumulated quite the collection of favourite fics on FFN and bookmarks on AO3. And I always really enjoyed S/I's, to the point where, when I wrote my reincarnation fic, it was on the back on the hundreds of SI/OC stories I'd read beforehand. And I'd seen a pattern, where people seemed to feel they could easily (or not so easily) cut it in a different world.

I, on the other hand, wasn't so sure.

It was super awesome and badass to read about people kicking ass and takin' names, but I had no illusions that I could do the same thing.

When I'd started 'Yeah, Kunai…', it was for the singular purpose of proving that decades of this life couldn't be so easily shaken in 'the next one'. And because I loved how people were so happy when you wrote things. But anyway! Just because you could wield chakra and do awesome ninja moves, didn't mean you could actually kill someone. Murder is murder, people.

So anyway, I wrote this fic.

And then this happened:

"This is an Emergency Announcement: All Passengers are to remain seated, with their seatbelt fastened-"

My flight back from Stockholm was…not great.

Then there was a yell of "BRACE! BRACE!" and we tucked ourselves down like those laminated sheets told us to.

The plane was dropping, I could frickin' feel it.

It was like when you first took off, the strange weightlessness, like going over the edge of a rollercoaster drop or that moment of flight on a trampoline, before gravity started yanking your ass back down again.

This was considerably less okay than those examples.

We were over the sea, a good few hours into the flight, and my best friend was crying loudly beside me. She was gripping my hand in her left and her phone in her right. I knew, without a doubt, she wished she had signal to call George.

The baby, that was seated two rows in front and had mercifully slept up until now, was screaming so, so loudly. The lights were blinking and the pilot was yelling loudly over the din, I couldn't make out a word.

That was when it all went very dark. It was a shock of metal, cold, cold into my limbs and then the crack on my head against Sophie's.

The ringing in my ears was the last thing I knew.

Well, up until I was aware that it was cozy warm again.

Was this...the hospital?

It was dark (I couldn't really feel my face so maybe my eyes were just closed?) and warm, like a deliciously hot bath. I tried to take a breath, see if I could smell the disinfectant from the sheets or my dad's cologne or anything.

One tiny issue? I couldn't take a breath.

Freaking out inside (if I could breath, this would probably be my first panic attack), I made to pat myself down, only I couldn't really move either.

Was I…paralysed, or something?

No, no, that wouldn't really account for the not-breathing bit, even in a coma you fucking breathed.

So, what? A dream or…?

No…surely not-

Something bumped into me and if I could have turned to look, I would have popped something in my spine for how much it scared me.

Feeling the way it was pressed against me, I could only assume it was someone else alongside me.

Maybe we were being held together?

I slowly lost consciousness again, my brain so sluggish and slow it honestly scared me.

Then again, these days when wasn't I nervous?

It must've been two weeks – no breathing, no food, very little movement beside my legs shifting, and yet still alive(?) – that I heard them.

Voices!

Quickly, fate decided to fuck me over, when I noted they were in Japanese.

Oh, for the fucking love of-!

Now, I didn't speak Japanese. I wasn't bilingual in any sense of the word, unless swears and asking for directions to the toilet counted. All I knew was some stuff from fanfic and Anime, like family names and 'Nani?'. I'd tried learning old Norse for my degree before I decided to take a break…which I never came back from, hehe.

Remembering how I did this in my fic, I swore revenge on the gods of irony.

I was, evidently, a baby in the womb, reincarnated, whatever you wanted to call it.

And, noting the fact that I wasn't in here alone?

My best description was…fucked!

…..

Being a foetus was next-level boring.

I mean, obviously I hadn't expected it to be a wild ride in here but…damn.

The next few months past excruciatingly slowly. Now, I was a super lazy person but even this was pushing me too far. I was warm and slept a fuck tonne and, when I was awake, I kicked as much as I could. One, to pass the time and two, because I was pissed off at this whole situation. Sorry new mum, it's not your fault but I'm doing it anyway.

Well, I did kick; up until my twin was a little shit and slowly shifted in front of me. What a fucking kill-joy, they better not be forming bad habits already…!

So, here we were.

With so much time to kill, I'd thought long and hard about what I wanted to achieve here, casting my mind back to all the fics I'd read about coping with reincarnation. Maybe they weren't the best source for consultation but, well, where else did people have highly rationalised discussions about rebirth coping mechanisms?

Thankfully, after years of furiously working to keep up with my sisters' brilliance and reading like a hurricane through the various fandoms, I had a pretty sound memory.

I'd thought through everything furiously. I thought about the chances of this being a dream, a coma, anything but real. I thought about if I'd tell anyone, try and examine how this could have happened, if I'd be born anywhere I recognised.

It only took me what felt like a few days to come to the conclusion to fuck it all.

I was going to be okay.

And you know why? Because I wasn't going to sabotage myself with things like existential crises or mental ages. I was gonna live my life like a fucking boss and no one was gonna try and convince me to tip toe through.

And this would be my life because there was no reason to torture myself thinking I'd somehow shoved myself into someone else's body, displaced their soul or whatever. I was being reborn, simple as that, and I would fucking get a grip and deal! This would be my life and therefore my family. No comparisons and no strangers. My face would be different from my last one, naturally, but it wouldn't be a stranger's.

It would still be me because, I knew, if I looked in the mirror, I'd see myself staring straight back out at me.

These new parents and this twin beside me were going to be new, different. They wouldn't be ginger and have a beard like my other dad. They wouldn't be super tall and strong like my other mum, or have freckles everywhere like both I and my sisters had had.

They'd be their own people and I'd hopefully grow to love them. If they were horrible and bad, well then. I'd already had a great family before; those memories would have to see me through and I'd just simply say "fuck you" to these ones.

I wasn't going to be some sissy and have a mental and emotional breakdown over something I couldn't control. I'd been famously good back home at rolling with the punches and being a rational person.

I'd be damned if I let a hurdle like this screw me over.

Coming to terms with what I lost was the first step. It would be harder, and even more real, if I waited until I was in the outside world again. So, I'd cried a lot, as much as I could in the womb, and thought about my parents. I felt such a deep regret when I thought of Sophie. She'd been older than me, taking a few years out before Uni, and George had had another year on us both. They were going to move in with each other in the summer, right after Amira's birthday. (Yes, they did hold a party for their fat, ginger cat.) I thought about the Japanese I'd heard and mourned my own language and culture. But then, I made myself think about kimonos and Tokyo and felt a bit better; I'd always wanted to go there and my cousin had promised to take me out for pocky if I visited him and his boyfriend, but I'd never gotten 'round to it. I'd lost so much, everything, but I'd be gaining somethings as well. A new life, a new family.

Even if the one I would be joining was a terrible one, I'd hopefully still have the tiny baby beside me out there too.

As the months passed and I gradually came to terms that this was really happening, things started to get a little bit…cramped. My mind helpfully reminded me of all the fucked-up things a damaged umbilical cord could do, horror stories provided by mum and Grammy, as my own and my twins were pressed against us, squashed as we were.

And then, one day, the warm water started moving.

As the daughter and granddaughter of midwives, I'd been a massive idiot and forgotten the most important part of pregnancy.

The birthing bit.

Aww, man!

It was loud and messy and reminded me way too much of the plane.

Whilst I'd read and written about the horror of being born, I had the double issue of a twin. Which meant triple the stress (stress for me, for them and then, also, for the both of us).

I'd never freaked out so much in my life, in both of them. It was exhausting and terrifying and so, when I felt the black creep along the edges of my vision, I bade a strategic retreat from the situation and passed out.

I came to with a slap and a scream.

Fuck, shit, fucking nope-

Wiped down with a cloth that felt like it was sandpaper on my tender skin, I barely even noticed how weird it felt to breath air again. I was, naturally, too busy making sure everyone knew how unhappy I was by screaming like a demon.

Wrapped in swaddling and carried around just added to the flames of my malcontent. Trust exercises were hard enough when you were physically able; being lifted around by giants when you couldn't move yourself and were the size of a loaf of bread? I was wailing for a cradle or something, just put me the fuck down.

When I was tucked into someone's chest – I felt boobs, probably mum – I swore that, if I ever had to go through that again, I'd have a heart attack. Mental note- ever help out with a birth in the future? I was going to be as secure and comforting to that new-born as possible. No fucking two handed lifts going on here, I'm talking both arms and against the chest!

Cracking open my eyes was a chore and a half, they felt swollen and wrinkly like I was E.T or something, but I really wanted to make sure I wasn't born into some crazy planet.

Mum was blurry, like when I'd made the mistake to try and swim without goggles, and the blue blob opposite me was probably my twin. Judging by hospital gender stereotypes with blanket colours, I came to the conclusion I had a bro. Cool, that's another new experience to add to the books.

Mum looked nice, surprisingly young with flawless (if sweaty) pale skin and spikey ash blonde hair. Paired with her scarlet eyes, I mused that she must be albino or something. The brown blob I identified as dad leaning over her shoulder, was an average looking man with warm coffee hair and eyes and with specs perched on his nose. In all honesty, he looked a bit green but very emotionally happy.

Well, so far so good, I'd say.

My new mum whispered to me and, even though I missed half of what she said, three things stuck out. I absently wondered if I could go back into the womb now please, where I was safe, warm and ignorant.

Kagami…my new name, I guessed.

Katsuki…my brother?

Bakugou….aw, shit.

So much for mum just being an albino, then.

….

I slept an awful lot the next few months.

It was marginally better than being in the womb, at least I could move and breathe and hear etc. Unfortunately, there were also some cons.

Like, ooh I don't know, being able to hear Katsuki scream and scream and scream?

Now, I was firmly in the fandom boat of 'Yeah-he's-a-little-shit-but-he's-my-shitty-son-so-back-off' and I knew that he'd done some terrible things and would grow up to be a supremely complicated person. This didn't change the fact that I adore the little devil and also…he cried so much, sometimes I'd start screaming too just to let out the frustration. He was a handful and that would never change, it was just the way he was. Whilst I knew that there was a chance he'd make a show of disregarding me, like he'd done with his parents, I knew I wouldn't let him. He might have made a point about 'not needing anyone' but he'd still loved his parents and accumulated a group of kick-ass friends as a 'Baku-squad'. Like, seriously dude? Goals, right there.

And my response to all this shit?

Like fuck was I gonna be left behind.

Katsuki, whilst a thorn in my side with his screaming, was my twin and we were all but glued to each other. We shared a crib, as was recommended with twins, and I woke up from my naps to his smol face.

Whilst screaming was an excellent way to vent my emotions, used as a coping mechanism in some ways, get attention from Kaa-san and Tou-san or just harmonise with my bro, I was in actual fact a very happy baby.

Well, in comparison to some demons…like my brother.

Despite only being 6 months old, Katsuki was a hellion. He threw his food, grinned like he'd successfully summoned Satan and didn't like words like 'No.' In comparison, I was rather sweet. With my memories of running and walking etc., I was able to start crawling from a reasonably young age. Without the worry of looking like a child genius and then hurried through the system to be an assassin, *cough* Naruto *cough*, I let loose a bit. Katsuki made a mess? I made sure I was firmly as innocent as possible by moving the fuck away.

The babyish betrayal on my twin's face when he started to understand how I was never getting into trouble, even when I helped, was adorable and I savoured it. It was nice to know that he didn't underestimate me.

Now, you would've thought I'd use my brains to get my brother out of trouble.

Nope.

Katsu, in the anime, would grow up arrogant and self-important, from a lifetime of not being in trouble and excused because of the power of his quirk. He could deal with some scolding and control, in my eyes. Also, making him acknowledge me as an equal in strength was an absolute must. And anyway, if he was left to run amok, then there was no way he'd grow. I'd loved who he was in the anime but I wasn't going to let him grow up so…isolated. His mindset had been different from most, basing people on strength etc., and I wasn't sure that was just from his treatment as a child. Nevertheless, I wasn't going to let him get away with misbehaving. I needed him to understand what he couldn't just do as he wanted as much as I needed to exert myself as not another of his 'stepping-stones' from a ridiculously young age. I didn't think he needed 'fixing' as much as he needed to know I understood how he saw and was making sure I fit into his world the way I wanted to.

When we were older I'd have to be much better about it. He was my brother and I loved him. As a baby though, he'd probably never remember this and he'd never really understand what was happening anyway. But babies were super susceptible to guidance etc. at this age so hopefully, I was making a social and mental impact.

So, aside from looking like a normal kid to my parents and a genius to my brother, life was really normal.

Well, if you ignored the Hero fights that were always broadcast on the news.

It was so strange, living a manga/anime as real life. Things weren't like the animation- they were fucking real and seeing All Might in real life?

I fucking choked. How the hell were his eyes still shaded like that?! Not to mention how huge he was? And the villain behind him?

I'd never laugh at Men In Black again…well, if I ever got to watch it again.

The villain – guy? Dude? Girl? I don't know – had purple spikes, like crystal, growing out of his spine like some alien porcupine. I was just getting into the fight when mum let out a curse and turned over.

Aww, he was just pulling one out of his shoulder, probably to use as a sword!

I got that, for babies, it wasn't exactly U-rated but Jeeze! It was just getting good…

Mum, for all her swears, was a responsible parent. So was dad, although he had bonus points for doing most of the cooking and not having a potty mouth.

Boo, for me, then.

Despite making me bored by turning off fights, Mum and dad were really nice. They talked a lot to us and laughed loads as well. I mean, I didn't really understand what was being said but I guess it was the thought that counted. Even if it just made me super aware of the hell that would await me when it came to learning the language properly. Grr.

Both of our parents were fashion designers, from what I could tell. I didn't think Mitsuki's job had ever been mentioned in the anime or manga but, from the amount of help she provided dad, I could only guess they must work together in some way.

Or maybe she was like me and just liked clothes.

They were both stay at home workers, except when dad occasionally met with his team to hash out the latest designs, and everything was very domestic. Mum left to go food shopping a few times a week and we'd had a nice babysitter what us a few times when they went out for tea. The babysitter, a nice lady from across the street called Suki, could make coloured bubbles from her skin. They all smelled different when popped (pink for strawberry, green for grass, etc.) and I thought she was lovely. I'd pop as many pink as possible (she quickly twigged on and started making just those ones for me) so I'd reek of strawberries for days after. Katsu wasn't all that impressed with her but I liked her! She'd put on the T.V when it was our bedtime and that was the majority of outside interaction we really got. I was relieved for the reprise, knowing the drama that would await us in a few years, and, in celebration for a normal baby-hood, made a point of getting Katsu into the habit of letting me hold his hand (so much so that he started holding his hand out when I was next to him – score!).

Sadly, my days of laziness would face a new challenge: walking.

I'd been trying to for ages, hating not being able to control where it was I was going, but I'd wanted to know just for my sake. I still wanted to be carried everywhere like a queen, thank you very much! And that's where I hit a road block.

When we were almost a year old, mum caught me trying to stand.

It had been an honest accident – I mean, I'd been crawling for months – but now the cat was out of the bag. And then, Katsuki, not to be outdone, the little shit, immediately tried to join me where I was holding onto the coffee-table legs.

The sight of the two of us, holding onto the table legs for dear life in our matching baby-grows and scowls, was evidently too much and Kaa-san barked out a laugh before calling for Tou-san.

The encouragement to walk was heavy from that point on and, two weeks later, katsu just about managed it.

In true fashion, he did it walking away, rather than to, our waiting parents. (That he was walking towards me was, *cough*, besides the point.)

Shown up by a baby, I resisted the urge to throw my biscuit at his head. My self-pride reared up and I found myself awkwardly stomping to meet my twin half way instead.

It felt like that bit in WALL-E, when the captain walks again, in all honesty.

A camera shutter had us blinking in union at Masaru, holding hands for structural support, and forever immortalised in our onesies and matching spikey hair.

Did I mention that we were identical?

Well, at least I knew there was an extremely good chance I'd grow up smoking hot (in more than just one way, hehe).

By the time we were almost two, Katsuki had started speaking in earnest and I was…awkwardly trailing along behind.

It wasn't my fault, okay? I just…I'd always struggled with languages and this one was even harder. Nothing was similar to English, not the spelling and not the structure- at least I'd had that with French! So yeah, I was stuck being the smart but quiet one whilst Katsu did all the speaking. And that boy, I swear damn, not the best for charming-points.

Even as a toddler, my brother was brash and arrogant. Sure, it was just the self-assurance and loudness of kids but, when stood next to me, I looked like the typical manga girl. You know, the shy and intellectual type who blushes and gasps at the slightest bit of attention or human contact.

R.I.P. my kick-assery.

So, to compensate for this, I made a point to learn as much as I could about the language. Downside? It was boring as fuck and I wanted to kill a bitch (preferably the one who sent me here) but, the upside? When Katsuki was told off for imitating mum and saying 'fuck' the first time, I silenced the room by saying 'shit'.

We were both sent to our room with no dessert but, seeing the impressed smile on katsu's face? Ooh, so frickin' worth it.

After my little show, our parents did a little reassessment of me, from what I could tell. The next time we went out to play, Katsu was still looking smug and I indulged him. He'd never, thankfully, treated me as or seen me like a dead weight. I mean, sure I was the older one by 3 minutes but Katsu was louder (not really by choice, I know) and it would have been easy for anyone to be overshadowed.

Katsu, however, knew better. He'd never, ever been without me and I knew he could see my smarts behind my eyes. I might not be able to say all that much, but the boy knew I wasn't a push about either. I'd never once stood down or back from him, never walked behind him and never so much as blinked at his tantrums.

The swearing had just been proof to him that he was right about me all along.

Ahh, who knew swearing was the way to Katsu's heart, ay?

Remembering an awesome 'Kacchako' comic on Tumblr, I let out a little giggle. So, maybe I wasn't the first then.

When we were almost three, I spotted a woman with green hair in the park. Even in a world of Quirks, I'd recognise that head anywhere and, knowing the plot, I knew it must be her.

Inko!

I couldn't believe it, Izuku was here! I knew he'd known Katsu since before their quirks (or lack thereof) emerged but hot damn, this was young. Fucking hell, I wasn't emotionally ready for this. Ah, warning; major plotline ahead! I internally screamed.

This was very different to my reactions to Katsuki and our parents. I'd had months in the womb to get used to the idea of a twin and new family. That that family just happened to be the Bakugou's was a shock to the system and that my twin was Katsuki? My hot-headed baby?

I'd been beyond surprised. But then I'd had years as a baby to grow with them and they were mine now, just as much as my last family had been.

Izuku was just…Izuku.

He was the central character of the whole storyline, the Quirkless boy who got a Quirk and had to deal with the legacy, basically. He was such a bundle of emotions and everything that I wasn't sure if I was going to cry, try and smother him in love or just run for the hills.

Gahhh!

I glanced around and, noting that my twin was waiting for me to follow him to the climbing frame, I set off after him, mind still whirling.

And that was another can of worms.

Kacchan and Deku…dare I interfere?

I knew myself well enough that, at the first sign of bullying or anything, I'd be in there like a shot.

Thinking back to the day Izuku was revealed as Quirkless, I knew I'd be stood in between him and the others in a heartbeat.

I could only pray that Katsu wouldn't hate me for it.

….

A/N- Yo! So, this story was a compete accident...but a happy one nonetheless. I've not really seen any Sibling!OC's or Sibling!SI's for this fandom so figured I'd just go for it. Hope my plane from Sweden doesn't actually go like this...Anyway! Hope you enjoy, please comment etc. to let me know what you think! Thanks for reading :)

P.S I won't be neglecting 'Yeah, Kunai...' so no worries, guys.