My first Big Hero 6 fanfiction! I rewrote and wrote this first chapter so many times, and had so many ideas: finally here it is!

Tadashi leaned on the railing on the bridge.

"I know what you're going to say," Hiro said, joining him at the bridge. "'I should be proud of myself because I'm finally using my gift for something important,'" he continued in a pretty terrible imitation of Tadashi's voice.

"No, I was just going to tell you your fly was down for the whole show," Tadashi responded.

"Ha, ha, hilarious."

Tadashi gazed off innocently into the distance as he waited for Hiro to realize he had been telling the truth. Just as he'd predicted, Hiro gasped and zipped up his fly, and then thumped his brother. Laughing, Tadashi resumed his position on the railing.

"Welcome to nerd school," he said softly to his little brother.

As Hiro thanked him for not giving up on him, Tadashi smiled. He'd always known that Hiro had a vast reserve of potential locked up in his enormous brain. He'd hated how Hiro had squandered that potential on illegal bot fighting when it could be put to use helping so many people. He wanted to show Hiro what good could be done, how lives could be saved, with the invention and development of new tech. Hiro's microbots – that was just the beginning. Tadashi wanted his brother to share his dreams, to help people, to make a difference. Together, who knew what they'd accomplish? How could Tadashi possibly give up on his little brother, his best friend?

Tadashi gazed out at the university. He'd always had big dreams – Aunt Cass had always called him her dreamer boy. And now, he would be working with his brother, together, at the university. The future was limitless.

Until, of course, it wasn't.

Alarms started to blare. Tadashi turned around, his fantastic mood evaporating like water vapour as he heard screams of terror coming from the fair. Not even bothering to check if Hiro was following, he raced off, back the way they'd come.

Coming in sight of the convention building, Tadashi stopped in horror. It was engulfed in flames. People were screaming and running in all directions. Even from here, the heat was almost unbearable.

At his side, Hiro gasped in shock. Tadashi raced forward, ushering people away from the fire.

"Are you okay?" he exclaimed to a fellow student who collapsed against him.

"Yeah, I'm okay," she coughed, "but Professor Callaghan is still in there!" She raced off.

Tadashi turned his eyes on the burning building. Callaghan, his mentor, who'd inspired him to put his skills to use helping people. Callaghan was in danger. And there were probably more in there, as well – he couldn't let them die.

That wasn't how he'd been raised.

As he began to rush forward, he felt a hand catch at his wrist. Hiro was holding him back. "Tadashi, no!" he cried.

Tadashi turned back. "Callaghan is in there," he told his brother. "Someone has to help."

He willed his brother to understand. He couldn't stay here in safety while lives were lost, while people perished. He had to save them, or die trying. That was why he had signed up for SFIT – he had to save lives, and make a difference. This was what he wanted to do.

With effort, Tadashi tore himself away from Hiro, ignoring his brother's cries and pleas for him to come back. As he raced up the steps, he felt his cap fly off, but he didn't stop to get it. People were dying. He had to help.

Bursting through the glass doors into the convention building, all Tadashi could see was fire. Columns of flame, reaching up and eating away at the whole hall. It looked like a scene from hell. Tadashi could barely breathe – the fire was consuming all the air. His eyes watered from the smoke.

"Professor Callaghan!" he choked through the smoke, stumbling further into the building. "Professor! Are you there?"

The building shook. Tadashi was a scientist – he knew what that meant. Abandoning the thought of saving Callaghan, he turned to run.

An explosion ripped the world into two. Tadashi was flung to the ground, groaning in pain. He tried to move, but every muscle hurt. He couldn't see, he could barely breathe, he was coughing and choking.

"Professor?" he mumbled. Opening his eyes, he barely managed to peer through the smoke. He caught a glimpse of a figure, rising up on a black wave of – of microbots?

He had to be hallucinating. Tadashi tried to move, but he was trapped on all sides by fire. There was nowhere to go.

This was it.

"Hiro," he whispered, closing his eyes. His brother's face flashed before him under his closed eyelids – Hiro as he'd been just minutes before, smiling up to him on the bridge. Hiro gazing at him in anguish, just before he rushed into the burning building. Tadashi felt overwhelming sorrow, sadness for the life he wouldn't live, at the chance of missing out on Hiro's growth. There was so much they could've done together. Hiro, his little brother, his best friend, who he loved more than anyone else in the world – and who he was leaving all alone.

"I'm sorry, Hiro," he whispered. "I couldn't help."

The ceiling crumbled, debris falling to crush him. The flames rose higher and higher. The fire turned the world orange and red and yellow, and then there was nothing but blackness.

What did you guys think? Reviews please!