Archive of Our Own

When Hikari was born, her father liked to say, it only took a few moments for her bright red hair to burst into flame.

The rest of her Quirk activated after she turned three, letting her entire body shift into becoming a living fire, all the individual flickers connected by Hikari’s mind. More sparks could jump off of her and ignite, but they’d all fizzle out again when she turned it off, just leaving bits of soot or charred patches behind.

When that started happening, her mother took away Hikari’s stuffed toys, most of them bearing damage from accidental fires. Learn control, she said, and you’ll get them back.

So Hikari practiced as much as she could, trying to master herself - but being able to keep her Quirk turned off most of the time meant it burned even hotter when she did use it. By the time she reached her fifth birthday, there weren’t any toys in her room, not even hard plastic ones, because they’d melt from being too close to her fire form.

“It doesn’t matter,” her father rumbled when Hikari tried to talk to him about missing her favorite doll and stuffed bear. “You’re old enough now to begin training, and that’s far more important than playtime.”

The first day she threw up, Hikari wished she’d never tried to master her Quirk at all.

A week before she turned six years old, her mother insisted on taking Hikari out of the house. The old woman who usually came to measure them for clothes hadn’t been able to come in a while, and apparently the lack of new outfits to try on was becoming a problem.

Hikari’s father didn’t like it. Then again, he didn’t like much of anything besides training and Hero work. Her mother refused to back down, though, hair and eyes glowing as she stood her ground and argued with him about going out and being waited on by professionals, and ‘not the old hag she hired that you’ve never bothered to let go, Enji!’.

So. A week shy of turning six, Hikari got to see real city streets for the first time.

Other people out and about didn’t pay much attention to them, except for one young man who caught Hikari’s curiosity, mostly by smiling and waving when her mother wasn’t paying attention. Surprised, Hikari didn’t have time to wave back before she was whisked away.

In and out of their big car, in and out of fancy buildings, in and out of changing rooms - Hikari was measured and talked over and dressed up in all different sorts of clothes at least a dozen times. And she couldn’t stop thinking about the young man who’d smiled at her.

His eyes looked like her father’s.

A week after Hikari’s sixth birthday, that same young man turned up at the front door.

Her father wasn’t home, busy with Hero work as the yearly Rankings were soon to be announced. Her mother also wasn’t home, away for the weekend at some place called a ‘spa’, and Hikari would be worried, except- the staff knew their guest. She watched from around corners as five different men and women greeted him, calling him ‘young Touya’ and smiling when he asked about their personal lives.

They all grew more solemn when he finally mentioned ‘the new golden child’, and with a jolt Hikari realized he meant her.

“Hikari-chan,” their head of housekeeping said with a slight bow, beckoning her out into the open. “Please, come meet your half-brother.”

...what?

Shit, the kid was tiny.

Touya knew, intellectually, that most six year olds were pipsqueaks, his own baby brother included. But there was a world of difference between being fifteen and carrying Shouto on his hip, compared to being twenty-two and staring down at his asshole father’s newest attempt at creating an unbeatable successor.

If the actual size weren’t enough, the kid had all the body language signs of someone used to taking up as little space as possible, trying to be unnoticeable. Wide eyes stared up at him, completing the impression of I’m small and scared and would like to go back to being ignored now, please.

He’d seen it too many times in the past year, getting started with his career as a social worker. It burned to see a member of his own family holding herself the same way.

Touya didn’t let any of that anger show on his face or in his own body language, though. Instead, he easily slid down to crouch in front of the kid, mouth curled into a lazy half-grin. “Hiya, Hikari. Bet the old man’s never mentioned me or your other siblings, has he?”

Golden-orange eyes grew impossibly wider, and the kid shook her head. Little sparks leapt out of her curly red hair with the movement, and a couple of the staff members gathered around them backed off a step or two.

Something in Touya’s heart twisted painfully. “Well, would you like to come meet them?”

“Ah, young Touya,” the woman in charge started to say, even as Hikari nodded, “I’m not certain that’s going to be allowed.”

The kid immediately shrank back in on herself, but he wasn’t about to be deterred as easily. “Well, are either the old man or his new wife around? No? Then I don’t see why I can’t take my baby sister right now to meet the rest of her family.” Several nervous glances were exchanged, and Touya added, “I don’t want to get anyone in trouble, but I’m not walking out of here without her, either.”

“...you still know the codes for the garden entrance, don’t you?” One of the groundskeepers asked. “We can- we can pretend we never saw anything.”

“Perfect.”

Shimo Shouto was thirteen years old when he first met his half-sister, and immediately decided he would do pretty much anything for her.

“Just keep the kid occupied for now,” his oldest brother murmured, after setting Hikari on the sofa and stepping out of immediate earshot. “I’ve got to send off a couple of quick emails, be right back.”

Shouto nodded, accepting his mission with all due seriousness, and sat down across from the six year old. “Do you- um.”

Hikari stared at him with wide eyes.

Conversing with small children, it should be said, was not something in Shouto’s usual skillset. His best frame of reference were vague memories of what Izuku and Hitoshi were like when the three of them first met, but even that fell a bit short of helpful, considering Hikari would be more like him at that age than- wait.

“Has Father started teaching you about Heroes?” He asked carefully. Hikari nodded, shivering once, despite the warm temperature of the living room. “Do you know who All Might is?”

His half-sister shook her head, and Shouto knew he’d found an excellent topic of conversation to engage her with.

By the time Touya came back, Shouto was perched on the sofa himself, and Hikari had likewise shifted, practically sitting in his lap as she stared at his phone with an awed expression. They’d gotten through a basic explanation of who All Might was, why Endeavor despised him, how the Number One Pro’s family were indirectly responsible for her four half-siblings escaping their father years beforehand - all the important things to know, outlined against a backdrop of numerous video compilations of All Might in action.

Touya snorted at them. “Why am I not surprised... Alright, Hikari, we need to pause the info-dump for a minute so I can ask you a couple of things about the old man’s ‘training’.”

Shimo Rei was forty-two years old when her oldest son committed his first kidnapping. He denied it, of course, but there was no getting around the small child sitting in Rei’s living room, looking very overwhelmed despite her other three children doing their best to make her feel welcome.

“He isn’t going to let this go,” she informed Touya once they’d retreated to the kitchen, voice more haggard than she would like.

“I don’t care! I don’t care if he and his new trophy wife have a dozen more kids, either, I’ll go back in and find evidence on him every single time to get them all out!”

“Perhaps, just focus on this one for now,” Rei said quietly, glancing back through the open doorway to the hall. Natsuo’s voice was the only one she could make out clearly, as he retold the story of some sports mishap at school a few weeks past.

Touya deflated a bit, though his scowl remained. They were past the point of it reminding Rei too much of her ex-husband, but- well. She didn’t like arguing with any of her boys, for multiple reasons. (Tucked inside her heart was an ever-persistent pain over what she’d done to Shouto, the guilt of losing her mind for ten seconds too long. Right next to it resided the fears of what she might do to Touya or Natsuo if the same ever happened again, if her oldest boy’s flames ever ignited in the wrong moment, or his rapidly growing brother inadvertently loomed at just the wrong time-)

Rei sucked in a deep breath, held it, and slowly counted to ten as she exhaled. By that time her hands released their white-knuckled grip on the countertop, and the last of Touya’s anger had faded, replaced by a concerned expression that made him look far younger than his age.

“What steps have you already taken,” Rei asked.

“Uh... filed a report of physical abuse, and some witness statements I got out of the staff about how she’s treated like a doll by her mother as well as comments on the bruises from training. Now that I’ve gotten Hikari’s account too, I can add that as additional evidence; the appeal to remove her from his custody is already in the system, I took care of that as soon as we got back...” Touya trailed off, still watching her. “You’re not- it’s okay that I brought her here, right?”

“Of course it is, sweetheart,” Rei immediately replied. And, honestly, it was. Not just because little Hikari was in no way responsible for Enji’s actions, but, if Rei didn’t know of their relation, she never would’ve guessed the girl to be her ex-husband’s child. Perhaps when her fire Quirk was fully active they bore a greater resemblance, but the curly hair and bright orange eyes were enough of a difference to keep her from flinching.

Though the sparks constantly coming out of said hair might take a bit of getting used to.

“I’ve still got that friend who offered to let me move in with him,” Touya offered.

“Absolutely not. We have more than enough room here, and having more caretakers on hand will help with your petition for custody.” Rei paused. “You are planning to put yourself forward, yes?”

“Damn straight I am,” her son grumbled, once more glancing at the door with a blush dusting his cheeks. “That woman might not hurt her, but she sure doesn’t take care of the squirt either, not like you did with us.”

Rei nodded, and started reaching for the supplies to put together a snack platter for her children. Her five children.

Takami Keigo was twenty years old and the Number Nine Pro Hero when he accidentally made friends with a literal dumpster fire of a human being, and it was only six months later he found himself being introduced to said dumpster fire’s baby sister.

“Wow, you’re a really little candletop, huh,” Keigo said with a grin, crouching down to offer the kid his hand. “Nice to meet you, Hikari-chan, I’m Hawks!”

The little girl solemnly accepted his handshake, but her gaze was pretty obviously glued to Kiego’s massive red wings. His grin widened a tad, and he detached a couple of feathers to float down and dance around her. Hikari’s eyes widened dramatically.

“Don’t worry about burning them,” Touya drawled, one hand resting casually on top of his baby sister’s head, despite the fact it was literally on fire. “He’ll moan and groan, but they grow back.”

Keigo pressed a hand flat against his chest and leaned back dramatically, wings flapping to keep him from falling onto his butt. “You burn Hawks? You burn his feathers like a turkey?! Oh! Oh! Jail for Shimo-kun! Jail for one thousand years!!”

Hikari, amazingly, huffed out a tiny, near-silent little laugh, and Keigo decided then and there he would absolutely die for this child if necessary. He looked up to crow over his victory, only to see Touya grinning from ear to ear - and not his borderline evil, I’m gonna enjoy messing with you grin, no, this expression was tender and heartfelt and soft.

Crap.

Maybe Hikari wasn’t the only one Keigo would die for.

Todoroki Hikari was a week away from turning seven years old when Touya-nii brought her to an empty apartment two streets away from where they’ve been living with the rest of their family, and asked what she would think about moving to stay with just him and Keigo-san.

It looked smaller than Auntie Rei’s home, but felt bigger with all the empty space. One of the bedrooms was painted a soft yellow color, and had a window that looked over the small neighborhood park Shouto’s taken her to before.

She looked over her shoulder at Touya-nii, and nodded once, decisively. His shoulders sagged a bit with the loss of uneasy tension, and her big brother smiled.

Hikari smiled back.