a bit of a dark AU where Tadashi survives (not my best work, but I tried)

"Callaghan?" I shouted as I ran into the burning building. Flames were everywhere around me, but I saw a straight shot through the room to the back entrance. I ran as fast I could, hoping that he'd somehow escaped and was behind the building, safe. Right when I opened the door and stepped out, the building exploded, sending me to the ground. My ears ringing, I blinked open my eyes to try to make out what was happening.

And there he was. Callaghan, standing there, alive and well. My instant relief was soon replaced by confusion as he turned around, Hiro's ESP band around his head. Before I could speak, he raised his arm, calling the microbots that hadn't been destroyed in the explosion. They swarmed around me, encasing me and raising me up into the air.

"What are you doing?" I shouted down at him. "Sir, it's me- Tadashi!"

"Tadashi?" Callaghan repeated as the microbots brought him up to my level. "What do you mean? Tadashi and myself were just killed in that explosion, don't you see?" he explained calmly, twisting my head around to see the flames that engulfed the building.

"What? No, I'm right here, and-" my eyes widened. "You're stealing Hiro's microbots," I stated, mouth dropped open.

"You always were such a clever little student," Callaghan chuckled to my horror. "Unfortunate for your brother, though. His idea had so much potential, but it had one fatal flaw," he stated as he turned his back.

My jaw clenched. "Oh really? What flaw?" I asked through gritted teeth. As much as I didn't want to believe what was happening, I had no choice. This was the reality of my situation.

He turned his head and grinned, a wild glimmer in his eyes. "I wasn't the one in control." My heart sunk even lower. This wasn't Callaghan, he was a good man, this wasn't happening, please, no- "But now, with your help, I will be," he continued cooly, as if he was talking about the weather.

"I'd never help you steal my brother's invention," I growled, trying my hardest to fight against the force of the microbots.

Callaghan turned around and clenched his fist, making the microbots squeeze me tighter. "I really think you will." He stepped up closer to my face. "Here's the deal- either you help me recreate the microbots and mass produce them-" he tightened his fist ever more. "Or, I can get Hiro to do it."

"What, threaten him? He's not stupid, you know," I said, letting out a forced laugh. The microbots were squeezing harder and harder with every passing second.

Callaghan laughed. "Oh, I know. That's why I gave him that acceptance letter, remember?" My eyes widened. "Oh, you do catch on so quickly! Hiro is so excited to come here… to be under my instruction…" he trailed off, leaving my mind to finish the rest.

"You'll also be thought of as dead," I stated suddenly, a grin coming on my face.

He shook his head with a sigh. "Not unless a certain, brave, big brother miraculously saved me," he corrected airily. "And I'm sure that there's nothing more that Hiro would love to do than to honor his dead brother by helping the man he saved to work on the microbot technology that could have also saved that beloved, dear brother."

I ground my teeth together angrily. He'd had it all worked out from day one. "Fine, then. I'll help you- on this condition: you leave Hiro and my friends alone."

Callaghan shrugged casually. "Fine by me- I'm dead, remember?" he said with a grin. He suddenly let me go, the my microbot prison falling like sand from around me. He turned his back away. "Be at the dock by morning. Your brother's life depends on it." And with that, he left on a wave of microbots, leaving me lying on the ground breathless.

I sat there for a few minutes, frozen. I'd just made a deal with a devil himself.

After a while, I started down a back alley to a pawn shop and bought a old, ratty hoodie. With the hood up, I walked down the back roads of San Fransokyo, listening to the sirens of firetrucks and ambulances wail in the dark of the night.

I walked with no purpose for about an hour, my mind completely blank. I didn't know if I should try to run, hide, go home, or hop on a plane to another country. Or maybe nothing at all. All I knew was that every block I walked down, I saw memories.

I walked past the shop I'd bought my favorite hat at, the restaurant that the gang went to every single Friday after classes. Past the museum that I took Hiro to when he was younger. Past the movie theater that Fred and Wasabi and I were at for every single movie during the summer. And eventually, I passed by the first place where I realized that I loved Honey Lemon.

Honey Lemon. I sighed at the thought of her. Was I ever going to be able to see her again? To ever get up the courage to tell her that I loved her? The answer to both was no.

Unless…

I looked up and found a nearby clock. I'd been walking around for hours, but I still had time before I needed to be on the dock. My feet didn't hesitate to turn and walk in the direction of Honey's apartment. My heart was an odd mixture of feeling heavy, yet as light as could be. I stared at the first floor apartment with a sigh. There was no way that I could get in without bothering her, and then she would know that I was alive.

The wind creaked a window. I blinked at it and saw that it was unlocked. Without thinking, I immediately climbed through and saw Honey Lemon asleep on her bed. I walked over and saw tears staining her face. She must have already heard.

I squeezed my eyes shut and shook my head at myself. I should've told her before it was too late. I reopened my eyes with a sigh. I leaned down to look at her closer.

"I'm sorry," I whispered, kissing her cheek softly. "I'm so sorry."

She hummed in her sleep, her head moving. "Tadashi…" she mumbled. Afraid she would wake up, I had no choice but to run.

I wiped away a single tear as I ran down the sidewalk, trying to get as far away as possible before she woke up. I would return to her and Hiro. One day…I promise.

With dawn breaking through the darkness of the most difficult night I'd ever experienced, I headed to the dock. Upon reaching it, I saw Callaghan waiting with the microbots.

"Smart boy- I half wondered if you would try to run," he mentioned as I walked up to him.

My teeth clenched together angrily at my next words. "Wouldn't think of it."

"Now, now," he chastised as the microbots began to carry us over to the island. Callaghan looked over at me with a knowing smirk. "That attitude's not going to keep your brother safe, now is it?"

"No sir," I ground out, hands fisting at my sides. I could feel my nails digging harshly into my skin.

"Good," Callaghan admonished with a grin. "This will be easy, then." He then dropped the microbots out from under me, leaving me to land roughly on the concrete. "Follow me," he instructed, leaving no room for argument.

I followed him through the abandoned island base, refusing to let my eyes look around the deserted labs in wonder. Finally, we arrived at one that contained brand new looking equipment. Just as I walked inside it, he turned around and shut me in.

"Have fun!" he shouted through the steel door. I slammed my fists against the door uselessly. I let out a ragged breath. I could do this. I had to do this.

I resigned myself to exploring the lab. I saw three deactivated microbots sitting on a desk beside a computer. Upon further investigation, I realized that whatever coding or instructions I put into the computer was sent directly to manufacturing robots in an old factory in San Fransokyo.

Having no other choice, I began my work on the microbots, trying to recall what little Hiro had told me about them. For the next two weeks, I did this, working tirelessly as Callaghan hovered around me tauntingly.

"Looks like you misplaced your trust in me after all, Tadashi," he would say. "I can only hope that your brother is doing well…perhaps I should give him a visit?" he would bluff. I kept my mouth shut, knowing that he was trying to bend me until I broke. But I wouldn't. Not today, not the next day. I was useless broken, and Hiro was smart enough to figure out Callaghan's plan eventually.

Once I figured out the makeup of the microbots, I then had to make a program for the robots at the factory to make them. With every sentence of code I typed, my regret grew. 'I'm so, so sorry,' I repeated continually, hoping that it would somehow make up for what I was doing. Production soon started, and Callaghan came in to see my progress.

"One at a time, Tadashi? Really? Is that all you can do?" he would say. "I thought you were smarter than that. I'm sure your friends thought that you were smarter than that, too." No matter how much I tried to speed up the process, Callaghan would insist that it be faster.

"I'm going to check on how many have been made so far," Callaghan told me one day. "I do hope for your brother's sake that it's more than I think."

I didn't hear from Callaghan after that. He returned, but said nothing to me of what happened. For the next few days following that, Callaghan was gone. He left the door to my lab unlocked, but every other door was sealed shut. I spent my time wandering the empty hallways, wishing that there was some way that I could get into a room, find a computer, and send a distress message. I'd already tried this on my computer, but the message was intercepted before it sent.

And suddenly, I heard voices coming down a hallway. Before I could shout, a swarm of microbots came around the walls and swallowed me up, carrying me back into my lab and sealing me in. I slammed my hands on the door, hoping that whoever it was would hear me. I heard several loud crashes and explosions and shouts before- silence. And suddenly, I heard Honey Lemon.

"Baymax! Baymax, stop!" she screamed urgently.

"Honey? Honey Lemon!" I shouted, banging on the door with more force. But to no avail. I heard rocket boosters take off, and then nothing. I crumpled to the floor. What had just happened?

Ten minutes later, the door clicked open, and Callaghan entered on a pillar of microbots wearing the mask he'd recently donned. "You should have seen them, Tadashi…they were all so brave," he taunted, looking down at me as if I was an ant. "Your friends all care so much about you, don't they? Especially your brother-"

"You said you wouldn't hurt them," I coughed, struggling to get to my feet. "You said-!"

"Yes, I did," he cut in calmly. "Did it not occur to you once that I would lie?" Callaghan asked, eyes stoney. "You should have taught your little brother to not meddle with people bigger than him, Tadashi…" he droned as he exited, slamming the door shut behind him.

I shouted. I screamed. I turned over my entire lab until all of my strength had left me. I sat there on the floor, staring blankly at the mess I'd created. And then it hit me.

I dashed to my computer and started changing the design. I inserted the weakest metal I could think of to replace the key components of the microbots, therefore making the microbots produced from that point on weaker than the rest. Assuming from the shouting that Baymax was with Hiro, Baymax should be able to discover this weakness.

I then started working on a much more daunting task- recreating the ESP band. I worked at this tirelessly for hours, recalling what Hiro had told me about them. After a constant twenty four hours, the ESP band was working and snapped around my wrist with wires running up to a chip on my head. With the level of energy it had, I should be able to override Callaghan's control over the microbots…

But only if I could get within a close enough range.

And thus commenced the building of my flight suit.

I'd been thinking over it the entire time I was here- it was the only way I would be able to escape. I'd been stashing whatever spare metal and parts I found ever since I got there if the opportunity ever arose to escape.

This was that opportunity.

Countless hours later, just when I was almost done, Callaghan called through the door. "I'll be back in a little bit, Tadashi! I just have some…errands to run!" he shouted as if going out to get groceries.

"Yes, sir!" I yelled back as to not raise suspicion. I looked over at the unpainted, dinged metal suit and sighed. Ready or not, it was going to have to be enough. I put it on and snapped the catches into place. Lastly, I placed my helmet over my head, concealing my face. I pointed my right hand at the metal door and clenched it into a fist. A rocket flew off my forearm and into the door, exploding upon impact.

I ran through the corridors to the exit, knowing that I had no time to loose. I activated the rocket boosters and set off across the water toward San Fransokyo. The closer I got to the army of microbots, the more the levels on my monitor rose. Just a bit closer, and I would be able to-

A hand on microbots slapped me down, and Callaghan raised me up to his level. "Oh, I wonder who this is!" he said comically. I looked down and saw Hiro and my friends staring up at me in confusion. "Was the mask really necessary?" Callaghan asked with a smirk.

"I could ask you the same thing," I spat back.

He shook his head and sighed. "You really should have learned by now, Tadashi-" he admonished, silently commanding the microbots to squeeze me tighter. He leaned forward and pulled off my helmet. I heard everyone gasp.

"Tadashi…" Honey Lemon breathed, her eyes wide. I looked down at her, my eyes taking in every detail. The microbots squeezed at me tighter, bringing me back to the situation at hand.

I knew that the levels were high enough for me to override him, but only for the ones around me. I quickly overrode his control, but kept myself in my prison so that he wouldn't know.

"I guess I forgot to tell you who recreated all the microbots, now didn't I?" Callaghan asked the group on the ground with a smirk. "Aren't you proud of him? I know I am."

"We'll get you out of there, bud!" Fred's voice shouted from his armor. I looked down again and saw Hiro simply staring at me in disbelief. Wasabi and Gogo looked ready to fight to get me, but Hiro just stood there, unable to move.

"I'm sorry," I whispered.

"Ah, such a touching moment," Callaghan drawled. "Too bad it has to end," he said, tightening his fist. But the microbots didn't move. "What? What's happening?" he growled, looking down at his hands.

I smirked, dissolving the microbots around me and sending them up into the portal above. "You know, I really am a lot smarter than you thought," I told him.

He growled. "You always were bright, Tadashi. But apparently not bright enough to stop all of the microbots," he stated as he raised up the rest of them around me in a cage.

I laughed to myself. If only he knew that he was putting them right into the palm of my hand. The microbots began shooting out at me, but I stopped them before they touched me. With each attack, I sent more into the portal. With only a handful of microbots left, I sent them up to wrap around Callaghan, using the rest to make a staircase for myself to walk up toward him.

"I hope you enjoy your time in prison, sir," I told him, reaching forward, taking the mask, and sending it crashing to the ground. Instantly, the microbots holding up the portal began to fall. I heard everyone scream, but as soon as the microbots began to fall, I grabbed them and reformed a structure to hold them.

The fog from the rubble cleared, and Honey Lemon stared at me. She ran forward and threw herself at me, sobbing. I buried my head into her shoulder, stroking her hair. "I'm sorry, I'm sorry, I'm so, so sorry…" I whispered.

She backed away and looked at me, her eyes broken. "How did you survive though? How are you alive?" she asked in a small voice.

"That's a story for another time, love birds," Gogo shouted, drawing our attention to the still active portal. Honey and I walked over to the group just in time to hear Baymax speak.

"The female patient is in there," he stated, looking into the portal. Hiro didn't hesitate before he got on Baymax's back to leave.

"Hiro!" I shouted, making him stop. "I'm- I'm sorry."

"Me too," Hiro said with a sad smile.

I laughed euphorically. "And I hope you finally learned your lesson, bonehead."

"Don't run into fires- got it," he joked tearfully, snapping his glass mask down. I watched as he and Baymax took off into the sky, then looped down into the portal.

When he came out minutes later, though, Baymax was gone.

And so life carried on. Callaghan went to jail, his daughter was rescued, I told Honey Lemon how I felt, Hiro helped me re-create my suit, and we brought Baymax back to life. And I've gotta say, I never set out to become a hero. But sometimes life doesn't always go the way we expec