because viper brought up a fun TVTrope and i'm a sadist

disclaimer: I don't own the copyrighted material within

The first time this happens, Tadashi is barely a teenager and Hiro's still tiny enough to fit into toddler clothes. They're downtown, Aunt Cass distracted by a street vendor sharing tips for making taiyaki, and Hiro's tugging on Tadashi's arm with all of his little-boy strength. "Dashi, Dashi!" His tongue skids on the shi and turns it into a di, "wanna taiyaki!"

Tadashi laughs, ruffling Hiro's fine hair and aching for his parents because they never taught him how to say no to Hiro's sweet tooth. "If you keep eating taiyaki, all of your teeth will fall out!"

"But Dashi," Hiro pouts and he's so small, Tadashi remembers translucent fingers wrapped around his thumb and tying all of his heartstrings neatly into Hiro's soul. "You can fix my teeths later?"

Tadashi thinks about it, wonders if Aunt Cass will approve. Hiro's vibrating at his hip, calling Dashi over and over with even the simple nickname jumbling in his mouth, until he stops. "Hi lady!"

Tadashi turns to see an older woman, older than his mother iswas, and she doesn't look too happy. "How old are you," her voice is rough and only gets rougher when Tadashi pulls out a wary thirteen. "Unacceptable!" Tadashi backs up as the woman pokes his chest, "You're still young enough to be bent over my knee and you've got a son?!"

Um. Oh. Erm. Tadashi blushes and fumbles for words but they're slippery like the ones against Hiro's missing teeth and he's powerless to defend himself against her tirade. He shouldn't be sleeping around with women when he's still but a child himself, how is he supposed to support a son when he should be in middle school, she ought to drag him home by his ear and teach his parents a lesson for letting Tadashi run so wild—

"Hey!" Hiro stomps his foot, "leave Dashi alone, mean lady!"

Dashi sounds like Daddy and Tadashi's daddy never let him run wild, always told him to be mindful of the tinytiny boy vibrating at his hip because he's Hiro's older brother, his niisan, the guardian of his world. Now and forever, Tadashi gulps past a sudden urge to cry and holds Hiro back before he can kick the woman. That's rude otouto, mind your manners.

Then Aunt Cass comes with taiyaki, and her face goes from cheer to concern at Tadashi's apple red cheeks and Hiro's bite sized tirade and ah, she takes the older woman aside and sets her straight. No no, Tadashi is Hiro's older brother, her nephews, Mae and Tomeo Hamada's sons and yes, those Hamadas, thank you for your condolences.

Tadashi hefts Hiro onto his hip so he can nuzzle Hiro's hair against his cheek, and inhales the crispy bread and sweet cream scent dripping from Hiro's greedy fingers. It's a silly mistake, no need to get upset when it will only set his little brother off.

The second time this happens, Tadashi's with his firstmaybeonly girlfriend Denise Ishioka, and they're sneaking little kisses while "watching" Hiro at the arcade. Hiro needed out of the house and Denise didn't mind the little hanger-on as long as she got to lean against Tadashi's growing chest. And at least this time Tadashi's brother isn't illegtimate to the older couple who witness Tadashi lecture Hiro for cheating at Sugar Rush. "Hiro, the rules were clearly no backwards drifting through Blowout Beach, you know about that glitch."

Hiro shrugs and avoids the angry glare of his no-longer racing partner, and Tadashi rubs his forehead, "What am I gonna do with you?"

"It's all good," The couple is the no-longer racing partner's parents, and the father grins, "Boys will be boys, right? But tell your son to at least pretend to be shocked about that glitch, eh?"

Tadashi blushes hard because he remembers taiyaki and angry old women and Hiro gives Tadashi an odd look. Denise saves the day by laughing and pinching Hiro's cheek, "He gets it from his tousan, no arcade game is safe."

The couple laughs and the no-longer racing partner whines about his parents being uncool before sulking off to another machine. Tadashi's blushing and stumbling too hard in his throat to stop the mother and Denise from mock-griping about their husbands, and when the father elbow bumps Tadashi and stage whispers, "He has her eyes, lucky catch," Tadashi kinda wants to die.

Hiro has their mother's eyes and Denise's eyes do look a little like them, is Tadashi projecting weird Oedipus impulses on his innocent girlfriend? The same innocent girlfriend laughing about shrugging off all her baby weight in a few months because her softhearted husband was too afraid to lug their son around? Tadashi sees into a possible future and it's too much when the baby looks just like tinytiny Hiro who's hiding halfway behind Hiro in search of an escape.

The couple eventually leaves and Denise hisses between smiling teeth, "White people are so weird, do we really look old enough to be Hiro's parents?" and Hiro laughs too hard too loud and Tadashi drags them out of the arcade so his heart can settle on an easy beat.

Hiro stills looks at Tadashi funny days later, and Tadashi's come to calling Denise his wife, and Tadashi's stomach clenches uneasy when both of their Mae-brown eyes flicker at his.

The third time this happens, Hiro's sore about not hitting puberty when Tadashi did, and he channels surly tween malice into a show. They're seeking out the perfect batch of leeks for Aunt Cass's current dinner adventure, and why do dark haired dark eyed old ladies think that Hiro is Tadashi's son, they of all people should know the strange youth permeating in San Fransokyo. Another old lady scolds Tadashi for letting his son out in the chill without a proper sweater, and the odd look's back on Hiro's face before it becomes the Look.

Tadashi groans because the Look means another behavioral meeting at school that Tadashi keeps getting called into because Aunt Cass needs Tadashi's support in reigning in Hiro's chaos.

Hiro smiles, cheeks bright and eyes sweet and completely evil, before whining, "Dad, hurry up, the good leeks are down here and Mom's waiting!"

In an instant every old woman is upon them, pushing their wares and pulling at Hiro's cheeks and swarming around Tadashi's still awkward limbs in search of whatever fathers looked like. They find him a bit wanting, instructing him to tell his wife to add more beef stock to their noodles at night and try these herbs, they'll boost his muscle growth. Tadashi's bright red and all of the old women's daughters nieces grandchildren giggle and titter, like Denise but even more vicious because Hiro's playing up how his otousan is a bumbling idiot who means too well.

Eventually they get their leeks, and a whole mess of other goods for free that Tadashi didn't even know existed, and Aunt Cass's eyes widen with pure joy. "How in the world did you get all of those from Old Chiang's market, those ladies are vicious!"

Hiro cups his chin in his palms and smiles angel sweet, "They all felt bad for my otousan and threw stuff at us."

Hiro and Aunt Cass cackle loud and hard, Mochi mrrowing under the table and Tadashi swears he can feel his face sizzle. Just like Mae, Aunt Cass shares her wild tales of her older sister to Hiro who soaks in the mischief and darn it Aunt Cass no, don't tell him that, he'll do it again and Tadashi feels so strange every time people mistake him for a father and Hiro gives him odd looks.

Hiro gives him one later that night, and Tadashi throws a pillow at his face to hide the hitch in his lungs. But that's alright though, because Hiro plays dirty in pillow fights and this is all brother to brother violence, Tadashi knows this just as much as he knows the uncertainty of the other title, and he brays his victory into Hiro's fine hair.

The fourth time this happens, they're both dead silent with Hiro's eye swollen and Tadashi's knuckles still seeping blood in the cracks. They're not going to the police, Tadashi's TA Abigail's told him about how apathetic the police are about bot fighters, underage and in danger or not. And they're not going to urgent care either, because people ask questions and Hiro just wants to go home before Aunt Cass wakes up and Tadashi doesn't want to tell him that Aunt Cass already knows, she's always known.

Tadashi's arm is wrapped tight around Hiro's shoulders, and every little hitch of air between Hiro's teeth makes Tadashi wish he'd had a knife. It's not enough to smash a hustler's nose clean through his sinuses, it's not enough when Hiro was alone in places that Abigail never went and where tinytiny boys should never be. His knuckles crack and sting but that's alright because Hiro's alive and warm against his hip, and when a bystander asks if his son's alright, Tadashi just nods.

Hiro doesn't give him a look or a Look, eyes fixed on their mud splattered feet, and Tadashi remembers helping Hiro tie his shoes. Their father taught him but Tadashi was the one to help Hiro perfect it, he's the one who taught Hiro how to read katakana and ride a bike and disassemble the telephones to see where the sound came from. Their mother's eyes reflect in Hiro's and Tadashi wishes that Hiro was his son just for tonight, because if he was then maybe his guidance would have more effect, maybe Hiro would listen to him and not go where hustlers and gangsters leer at newly fourteen year olds.

Their house is far away from the lower districts, and Hiro stumbles up a hill. Tadashi hefts Hiro onto his back, and another one of those cursed old ladies spies them from her alleyway, telling Tadashi that in her day, her father would tie her to his chest so she wouldn't slip. Tadashi nods and Hiro flinches when his black eye brushes against Tadashi's neck, and they don't have string but Tadashi's belt will do. Tadashi likes the thickness around their waists, assurance that Hiro won't fall where Tadashi can't catch him.

Because that's his job, he's Hiro's older brother his niisan his guardian, and maybe it feels like fatherhood when Aunt Cass can only do so much and all of the world turns to Tadashi to keep Hiro alive. Would their parents hate him terribly if he kisses Hiro's dangling palm, wishing for taiyaki and tasting brick wall dust when Hiro scrambled away from the hustler? Hiro sniffles and Tadashi walks them home.

Aunt Cass pretends to sleep and Tadashi washes blood crusts from his hands and Hiro's cheek with too hot water. Hiro lingers by his bed until Tadashi pulls back his covers, because this is the first time when Tadashi's heard Hiro scream not in wanting for Tadashi but in wanting for someone please help me please, and Tadashi would never dare to turn him away now. Hiro's knees are knobby and cold, and Tadashi only half hears Hiro's tiny "I'm sorry" vibrate against his collarbone.

Hiro will do this again, Tadashi has no doubt because Hiro's is Mae and Tomeo's son and Aunt Cass has too many stories of them. So he holds Hiro close and nods anyway, listening to Hiro's breath turn shis into dis between his teeth and aching for their parents to finally come home.

One day the Big Heroes go up against a villain that Fred decides is true evil. She's evil because her army of androids are soaked with chemicals that trick the victim's brain into hallucinating the appearances of loved ones, so they won't fight back. The Heroes fight back anyway, Fred blasting Heathcliff with fire and Honey melting her little primos y primas to the concrete and Gogo dashing against her eomeoni and Wasabi slicing his momma in half and Nene wrapping a meteor hammer chain around her oneesan's neck and Abigail crash landing against her wayward father.

Hiro doesn't fight, and he's stabbed before Marys can scream into their intercoms, and in the midst of the chaos Baymax very calmly points his rocket fist at the cackling villain and fires. She's down, Wasabi doesn't want to look because it's too similar to a nightmare locked away on Akuma Island, and Nene assures them that as long as she's breathing, she's secondary to Hiro.

Gogo races to Hiro and he's bleeding everywhere, out his mouth out his nose out the sinus corner of his left eye, and the android chemicals seep thick and hot into the wound in his chest. He pasts his lips for air and stutters out a di, and everyone watches Baymax try to save Hiro's life. Not again, not a Fujita blade but something so much more evil because Hiro's pupils dilate deep past Mae-brown and he chokes, "Dashi?"

It sounds like Daddy and Honey sobs into her hands. Marys has the paramedics coming and Hiro's going to live he must, but for now he's drowning in blood and chemicals and Hiro asks, "So hot, w-why so much ash? Tadashi, Dashi?"

The Heroes all look at each other, because what should they say? Wasabi shudders once twice three times when Hiro's tinytiny fingers wrap around Baymax's thumb, and Gogo grits her teeth, "It's alright, Tadashi's here."

It's a horrible lie because the only thing here is the aftermath of evil, but Hiro smiles bright and red. "Dashi…" blood trickles and Hiro exhales, " 'tousan, 's cold."

He goes still and Abigail can't remember if Nene cried at the hospital when Kanon died, but she's crying now along with Honey and Wasabi and Gogo and Fred and herself, and cold unease grips at their stomachs. Marys asks in a small scared voice in their ears, "But wasn't Tadashi Hiro's older brother?"

No one answers. Instead they help Baymax keep Hiro alive until paramedics finally come and they're left kneeling around a pool of blood and memories. They're silent, flinching, and Abigail finally answers, "What's the difference?"

Hiro recovers and no one talks about what happened, but Hiro changes up his shrine rituals, dipping his bows deeper and lingering. It's his own ceremony, after all, no one needs to know the meaning of the odd looks he gives Tadashi's portrait; let him vibrate against the hip of his guardian in peace.

lol this is all over the place