A/N: Hello readers! So, this is my first Big Hero 6 fanfiction (actually my first fanfiction in a long time...go me). This "what if?" idea has been festering in my head ever since I saw the movie, and I just had to put it into writing. Anyways, hope you enjoy.

Disclaimer: I am not affiliated with Big Hero 6, Disney, or Marvel. These characters are not mine; I own nothing except this AU.

"Someone has to help."

Those four words rang painfully in Hiro's ears. Of course Tadashi would say something like that. Tadashi, the golden boy, the selfless one, the one who would risk everything he had to save the people he loved. Always the protector, the savior, the hero-never anything less. Behind him, the flames broiled and lashed at the windows of the exhibition hall, flickering in his determined eyes. His brow was set, and his baseball cap cast a stony shadow across his face.

The scene around them had gone eerily quiet. Even the vicious roar of the flames dulled down to a whisper as Hiro stared pleadingly up at his brother.

And then, Tadashi was gone, racing up the steps towards the burning building.

But Hiro wasn't anything if he wasn't stubborn.

"TADASHI!" he all but screamed, lunging after his brother. His hand caught the back of Tadashi's blazer.

"What-" Tadashi whirled around, his eyes wide. "Hiro, I told you, let me-"

BOOM.

The two brothers flew backwards, crashing into the pavement. Tadashi's head cracked against the cold concrete, stars swimming in his vision as he tried to regain his bearings. "Hiro…" he mumbled. "Hiro!" His ears felt like they were filled with cotton, still ringing from the sound of the explosion. Sirens wailed in the distance, but all Tadashi cared about was the hazy sound of his brother's voice, still screaming out his name.

"Tadashi!"

"Hiro…"

Blazing embers rained down upon them, chunks of burning rubble and ash like snow. The exposition hall had begun to collapse.

"Tadashi!"

"Hiro!"

More people were coming now, paramedics and firemen frantically barking out orders. Weakly, Tadashi felt his hand brush up against a familiar hoodie-Hiro's hoodie.

"Hiro…" He carefully lifted up his head, suddenly aware of a wet feeling trickling down his neck.

His younger brother hurriedly crawled closer, one hand clutching Tadashi's signature baseball cap close to his chest. "C'mon," he coughed out. "We-We gotta go."

Tadashi nodded, dazedly trying to stumble to his feet. Almost immediately, though, his knees gave way, and he collapsed back down onto the pavement. Smoke burned through his lungs, the ash stinging his eyes. Quickly, Hiro slung his arm beneath his brother's chest, hauling him to his feet.

"You-You alright?" Tadashi asked, wrapping his arm around Hiro's shoulders in order to keep himself steady.

Despite himself, Hiro let out a short laugh. "You're really the one asking me that?"

Tadashi chuckled weakly in response. "I have to, I'm your older broth-" He broke off in a violent fit of coughs, and Hiro quickly moved to steady him.

Paramedics soon swarmed around them, quickly taking Tadashi and helping him into an ambulance. Hiro watched his brother go nervously, barely paying attention to the paramedics fussing around him. Blood had soaked through the elbow of his sweatshirt, but he hardly registered the pain. All he could think about was Tadashi.

Tadashi was going to be okay.

He had to be.

If there was one thing Hiro hated, it was hospitals. The sterile smell stung his nostrils, even more so now with the ash and smoke still infesting his lungs. An unbearable silence pressed in on him from all sides. It was far too tense, too nervous waiting in the lobby; if nothing happened anytime soon, Hiro swore he would scream. The pristine white walls, the shining tiles, the harsh light of the parking lot's street lamps flooding through the windows all seemed to mock his pain as he waited anxiously for news on his brother.

"Hiro, please stop pacing," said Honey Lemon gently from her seat. "You need to rest-"

"I can't!" he snapped, much more harshly than he intended. Nervously, he tugged a hand through his already messy black hair, letting his eyes slip closed for a moment. "What if Tadashi's not okay, o-or he's hurt really badly, or…"

"Dude, chill," Gogo remarked, her legs draped across the cold metal arm of the lobby chair. "You saw Tadashi get into the back of the ambulance, right? He'll be fine."

Hiro swallowed back the lump in his throat. Tadashi had taken the brunt of the explosion when it hit; while Hiro only had a scraped elbow and a couple of bruises to show for it, his brother had at the very least a head wound. Hiro may not have been well versed in medical science, but from the way his brother was stumbling around after the explosion, he figured it couldn't have been good.

A doctor called for the Hamada family, and Aunt Cass quickly sprang up and hurried over, her hands clutched to her chest in fear. With a sigh, Hiro sank down into the vacant seat, slumping wearily against the hard plastic. How long had they been here? Three hours now? Four? Wasabi had already left, insisting that he had to adhere to his precise sleeping schedule but giving the Hamadas his condolences anyways, and Fred was snoring comfortably in the corner, sprawled out across three different chairs. Both Honey and Gogo were still relatively alert though, with Honey doing her best to comfort both Aunt Cass and Hiro. Gogo just simply refused to leave.

"Hey," she said, gently nudging Hiro's arm. "It's be okay. Tadashi's a strong man. He'll pull through."

Hiro frowned, fiddling absently with the zipper of his jacket. "Yeah, but-"

"Hiro."

Hiro's head shot up at the sound of Aunt Cass' voice. "The doctors said we can go visit Tadashi now," she told him.

Quick as a flash, Hiro leapt out of his seat and scrambled over, scrawny limbs flailing as he rushed to Aunt Cass' side. "Where is he? Is he okay? What happened to him?" Questions tumbled frantically out of the young boy's mouth, his brown eyes wide.

Aunt Cass chuckled softly. "Whoa, hey, slow down kiddo," she smiled. "Tadashi's fine. He had a concussion and a bad cut on the back of his head, but the doctors were able to stitch him up, and he'll be as good as new in no time."

Relief washed over Hiro's face. "Oh thank God." Quickly, he turned around and gestured to the rest of the group. "C'mon!"

Hiro and Aunt Cass hurried through the winding hallways, closely followed by Honey, Gogo and (a still rather groggy) Fred. Eventually, they came to a stop in front of a room labeled '614'.

"Tadashi?" Hiro called out tentatively, pushing the door open a crack.

His brother lay propped up in the hospital bed, casually flipping through a magazine one of the nurses had given him. A thick bandage was wrapped around his head, but other than that, he looked perfectly fine. Just normal, calm, collected Tadashi-even his hair still seemed perfectly combed. Unbelievable.

Tadashi glanced up at the sound of his brother's voice. "Took you long enough, bonehead," he joked, setting down the magazine.

"Hey, you're the one calling me bonehead?" Hiro replied, one eyebrow raised as he walked closer. "You're the one who tried to run into a burning building."

Tadashi pursed his lips in mock thought. "True, true."

Hiro stood at his brother's bedside for a moment, rocking back and forth on the balls of his feet, before pulling him into a tight hug. "I'm so glad you're okay," he mumbled.

Tadashi smiled, gently returning his embrace. "Me too." His eyes flickered over the rest of the group standing there, and a worried frown slowly formed on his face. "Hey, is everyone else alright?" he asked. "What happened? Did they find Professor Callaghan?"

Honey and Gogo shared a look. "Tadashi…" Honey began, hands fumbling with the strap of her purse. "The firefighters looked everywhere, they really did, but…"

"They couldn't find his body," Gogo interjected. " Professor Callaghan's dead."

Tadashi's heart dropped like a stone.

A/N: So, there you have it. I apologize now if I didn't get the characterization quite right; I'm still struggling to get a full grasp of these characters. Hope you enjoyed, please review if you can!