HEADCANON!

Similar to the headcanon in Ears and Tail 04, Hiro is fluent in both Japanese and English. Tadashi was the one to teach Hiro the Japanese words to things, and Aunt Cass was the one who taught Hiro English. Also, due to the larger age difference, Tadashi was born way before Hiro and therefore learned more Japanese from their parents before they passed away.

(I'm about to make you sad, so buckle in.)

In the canon, Hiro and Tadashi's parents passed away when Hiro was three. In this mini-series, Hiro is two years old. This means that Hiro has almost no recollection of his parents at all. But Tadashi does. He's a lot older than in canon when his parents die, and because of that, it is a more painful and traumatizing event, as he better understands the concepts of death at his age (maybe late teens?). This, however, did not mean he was emotionally mature – or prepared – for something like that to happen.

This brings us to the reason why he made Baymax. Tadashi was scarred from his parents' death and sees Hiro as the only family he has left (excluding Aunt Cass and Mochi). If he loses Hiro-

He won't even think like that, it scares him so bad. He specifically makes Baymax the Healthcare Companion with Hiro in mind, his mindset that of a dying man. He never knows what will happen to him (like he never knew what would happen with their parents), and as a result, he fears every day that he may leave Hiro alone (even though he would never willingly do so). To help ease his fears, he creates his greatest invention – a nurse bot with an advanced AI that would grow right along with Hiro.

All of this ties in with Handprint 02, in which Tadashi vows that 'for now' he would love Hiro with everything he could give.

He just doesn't know that Hiro's willing to give back.

Handprint 04 - せかいいちのにいちゃん

Human/Regular AU

(Baby!Hiro and College Student!Dashi)

Ding-ding!

Tadashi sighed heavily as he stepped into the café, the little bell attached to the door ringing pleasantly to announce his arrival. He was relieved to finally have made it home after a long day at SFIT; he swore, one of these days his friends were going to kill him.

One run in with a chemical explosion, a few mag-lev disks almost hitting him in the head, a couple of plasma-induced lasers singeing off the corner of his eyebrows and half a moldy-sandwich later, had Tadashi practically convinced he wasn't going to make it home that evening.

He was never volunteering to be their guinea pigs ever again.

Capital E in Ever.

"Welcome home Tadashi!" Aunt Cass chirped from behind the counter, hands working up a flurry as she fulfilled customers' orders with meticulousness coming only from long hours of work. "How was school today?"

The college student smiled - though it came out more as a grimace - and rubbed at the back of his neck. He gave a one-shouldered shrug. "I-it was okay," he admitted. "Just a few mishaps in the lab, nothing too serious."

His aunt flashed him a winning smile from over the head of one of her patrons. "Oh sweetie, sorry you had a rough day. If it makes you feel any better, Hiro has a gift for you!"

Tadashi felt warmth settle in his chest that spread out at the thought of his little brother. "Hiro made something for me?" he asked, lips quirking and brow rising.

Aunt Cass shot him an ecstatic grin. "Oh, you're gonna love it! He's been wanting to give it to you since this afternoon. Poor thing was so excited, he burnt himself out just vibrating with anticipation!"

The elder Hamada let out a laugh. "Did he at least take his nap for today?"

"I believe he's doing that right now," Cass giggled, shaking her head in fond amusement. "You might want to wake him up, or else he won't be able to sleep tonight." She rolled her eyes in good humour. "God knows how much of a headache that will be."

Oh, he knew alright. Sharing a room with an overly charged ball of energy during the middle of the night did wonders to his sleep schedule. The last time Hiro had taken a late nap, Tadashi had pulled an all-nighter with little else but Hiro's soft giggles, mischievous brain and dexterous hands to nag him into worried-wakefulness every half hour.

Tadashi shuddered at the memory and sent a slightly perturbed glance at his aunt. The woman merely shooed at him and gestured up the stairs, knowing smile still plastered on her face.

Climbing the two flights to the attic-turned-loft, the older Hamada slipped his book bag off his shoulder and shimmied out of his jacket and cardigan. Carefully folding his clothes and placing his stuff to the side of his bed, he shuffled past the paper divider into Hiro's part of the room.

"Hiro," he called softly, peering over the edge of his baby brother's crib. Soft snores and even softer features greeted him. Hiro was cute when he was sleeping – all chubby body and rosy cheeks and fluffy raven hair. The elder reached out to brush the sleeping child's bangs back. "Hiro, wake up," he cooed, thumb running over soft, poofy cheeks.

The toddler's eyelids sluggishly fluttered open, soft brown roaming over empty space before looking up into similar chocolate hues. A dopey smile crossed his face and Hiro slowly rolled into a sitting position, a massive yawn heaving out of his small body. "Okaeri," (Welcome home,) he sighed, fist rubbing blearily at one eye.

"Tadaima, Hiro," (I'm home, Hiro,) Tadashi grinned tiredly, stooping to lift Hiro out of his crib. The child giggled and clung to his brother's neck.

The elder of the two stifled a yawn in his brother's hair and squeezed the little body in his arms tight –Hiro squeaking into his shoulder and hugging back. Tadashi couldn't help the genuine smile that softened his expression. No matter what, Hiro always managed to make his day a little brighter. "Were you good to Aunt Cass while I was at school?" he asked, poking his sibling on the forehead. Hiro scrunched his nose and went cross-eyed trying to follow his brother's finger.

Chuckling, the college student bounced the toddler and repeated the question. Hiro grinned at him, seemingly more awake. "Yeah! I made you a present!" he cheered, enthusiasm beating out sleepiness.

The older Hamada hummed in thought, a playful glint entering his eyes. "Did you now?"

The child in his arms nodded his head excitedly, dark hair flying wildly about his face. "It's the bestest thing you'll ever get! And I made it!'

Lifting a brow in question, Tadashi shifted Hiro to his lap as he sat down on his bed. "Jibun de?" (By yourself?)

Hiro snickered into his neck. "Un!" (Yeah!)

The elder quietly mock-gasped and squinted suspiciously at his sibling. "Uso," (I don't believe you,) Tadashi teased, trying to smother the smirk that threatened to find its way onto his face. He had a clue as to what kind of present he was going to get; the smell of burnt sugar lingering on his sibling sort of gave it away.

The two year old gave him an affronted look. "Hontou! Uso jai nai," (It's true! I'm not lying,) he whined, small hands tugging at his brother's shirt.

Tadashi pursed his lips. "Hontou ni hontou?" (Really really?) he asked, eyeing Hiro knowingly.

Round chocolate orbs drifted to the side and a blush rose on those already pink cheeks. "Well... M-maybe just a little help," he admitted shyly, eyebrows scrunching and button nose wrinkling.

Laughing at the admission, Tadashi pulled Hiro close and placed a kiss on his forehead. "It's okay; anything you and Aunt Cass made is bound to be good."

Hiro's eyes sparkled. "It's in the kitchen!" he crowed happily, excitement back two-fold. The older Hamada obligingly got up and carried them down the stairs to their little kitchen and moved to place the toddler in his highchair. Before Hiro's feet could even get through the holes meant for the legs, the kid was pulling out the puppy-dog eyes and whimpering sadly as he clutched desperately to the front of Tadashi's shirt.

"Alright, alright," the college student sighed, acquiescing to his brother's non-verbal plea. He shuffled them around so that Hiro was rested on his right hip and his dominant hand was free. "So are you gonna tell me where the present is, or is Nii-chan going to have to find it?"

The younger Hamada stifled a giggle in Tadashi's ribs and murmured something incomprehensible.

"Hmm?" the elder hummed, stretching his neck down so he could bring his ear closer to his brother. "I couldn't hear you. Don't speak with your mouth full," he chuckled. Hiro laughed.

"It's in the cookie jar!" the toddler said as he pulled back from his position buried in cotton clothing. A chubby finger pointed at the china pastry container sitting innocently on the counter by the spice rack.

Tadashi grinned and walked over to it, amusement building as he watched Hiro – as Aunt Cass had put it – vibrate with excitement the closer he got.

"In here?" he asked, hand stilling over smooth porcelain.

"Yes!" Hiro practically yelled, now visibly bouncing against his side.

"Just making sure," Tadashi mumbled, a pleased laugh slipping from under his breath. He lifted the lid and peered in. At the very bottom of the jar lay one cookie. "It looks good Hiro," he said earnestly. He picked it up to inspect it.

It really did look good. The center was a light golden colour – no doubt thanks to Aunt Cass – and the edges were a darker, almost burnt brown – most likely the handiwork of his brother's short attention span.

Hiro fidgeted in his arms. "T-turn it," he demanded in a gentle – almost timid – voice. Tadashi glanced at his brother and found the child's cheeks glowing a soft red. Turning his wrist, Tadashi looked on the other side.

There, in large, shaky hiragana written in red icing where the characters spelling:

せかいいちのにいちゃん

"… Sekai ichi no… Nii-chan…" he read disbelievingly, chocolate orbs growing wide. Tadashi felt his chest constrict and a lump lodge itself in his throat. Heat burned behind his eyes. "Shinjirarenai," (Unbelievable,) he laughed breathlessly, smile watery as he repeated the words in his head.

Sekai ichi no Nii-chan.

"I love you," Hiro said simply – as if it were just a matter of fact. He turned his face upwards and stretching to all his toddler height, pressed a light kiss to his brother's cheek.

Hand trembling slightly, the elder Hamada placed the cookie back in the jar and hugged Hiro with as much warmth as he could muster. The younger Hamada buried his face into the other's shoulder and hummed contentedly.

"I love you too," Tadashi said at length, voice thick and words tumbling around and past his tongue.

Sekai ichi no Nii-chan.

Hiro rubbed his face into the crook of his brother's neck and sighed happily, gap-toothed grin pressing into his sibling's skin.

If a tear or two escaped Tadashi, they went unnoticed by both boys, the words written on the cookie playing on repeat.

Sekai ichi no Nii-chan... World's Best Big Brother.