A/N: When I watched the movie the first time… Well, I was actually quite a bit upset that Hiro gave up his revenge scheme so easily. The second time I was a bit more forgiving, but the idea stuck with me.

Because, well, if I thought someone had killed my brother or left him to die, and then said something so selfish about it…. Well, I would have serious doubts about the safety of that person, to put it mildly.

But I suppose Hiro is a better person than me.

Blood on His Hands

Hatred coursed through him like the sweet urge of invention, a fiery determination to accomplish his objective – except blown out of proportion, thousands upon thousands of times more intense, wild, unrestrained. He could hear his heart thumping between his ears, the rapid expansion of his rib cage, out and in. His older brother's friends' shocked gasps. None of it mattered.

He had expected Krei to be behind the mask. He was not.

It was Callaghan.

Callaghan, who was supposed to be dead. Callaghan, who was supposed to have perished in the fire. Callaghan, whom Tadashi had died for.

Callaghan, whose harsh, callous words echoed in the deafening silence, bouncing from metallic wall to metallic wall.

"But… Tadashi… You just let him die…"

"Give me the mask, Hiro."

"He went in there to save you!

"That was his fault!"

Throwing the blame to Tadashi. His older brother. For caring. For being a stupid hero. For trying to save Callaghan. Callaghan, who was still living when his brother was dead. Callaghan, who didn't care for his brother's death. Callaghan, who had let him die. Callaghan, who...

Callaghan.

The word became an item of dark revulsion, of all that was bad and evil. The enemy.

Suddenly, everything was clear, in crystal focus. His gaze snapped to Callaghan's face, his feet slowly backing away to Baymax as a snarl formed on his own lips.

"Baymax." His voice was full of unbridled fury. "Destroy."

"My programming prevents me from harming a human being," the robot protested.

Irritation.

"Not anymore."

His arm snaked to the access port, tearing away the green chip – Tadashi's chip – and throwing it uncaringly to the floor.

Clack.

"Hiro, this is not what…"

He slammed the access port closed.

Objective complete. Obstacles removed.

"Do it, Baymax!" he barked, small child's voice full of malice, anger, hatred. "Destroy him!"

.

.

.

He stared at his hands blankly, wondering what he had just almost done, finding that he couldn't bring himself to regret it.

All he could think was that they had stopped him. Honey Lemon, Wasabi, GoGo, Fred. Stopped him from avenging Tadashi's death.

He glanced up at Baymax, to the access port where Honey Lemon had put back in the green chip. He felt his fists clench in anger, and stood up. His feet led him to Baymax.

He pressed on the access port. It didn't open.

His eyebrows furrowed, confused. He pressed again, repeatedly. He took off the armor, tried again. Still nothing.

Why wasn't it working?

"Will terminating Professor Callaghan improve your emotional state?" Baymax asked, voice so level and calm.

"Yes," he snapped. Then – "N-no. I don't know."

Frustration. Frustration at Baymax for asking such a stupid, logical question. His hands moved forward to claw at the port again. If he rotated it, would it work? "Open your access port," he told Baymax, desperate, because if it didn't open, it would mean that he was helpless. It meant that he was wrong. It meant that the world around him would fall apart, because Tadashi is dead and it's Callaghan's fault.

"Is this what Tadashi wanted?"

"It doesn't matter." He tugged at the port, willing it to open.

"Tadashi programmed me to –"

Something in him broke.

"Tadashi's gone!" He found himself leaning into the robot's frame, as if all of his strength had suddenly left him. The words echoed into silence. "Tadashi's… gone," he said again, a lump in his throat.

"Tadashi is here."

Such innocent words. He remembered the robot saying them earlier. It drove a familiar spike of pain to his heart, another heavy reminder of his loss.

"No," he said, closing his eyes. "He's not here."

It was cruel of Baymax to say something like that. Cruel, and heartbreakingly sad. Did he even know his creator was dead?

"Tadashi is here," the robot repeated.

A whine, and suddenly a screen lit up on Baymax's chest. His eyes flickered open, his grief-addled mind unable to process what it meant.

Tadashi's voice spoke, and it was like seeing light after centuries of blindness.

"This is Tadashi Hamada," he began, "and this is the first test of my robotics project."

Hiro stared wide-eyed at the screen.

Tadashi. He…

He recorded this?

He thought there was something wrong with the screen because Tadashi's image blurred, but no, it was because his tear ducts were leaking water. Sniffling, he wiped his eyes so that he could see his brother's face clearly, even as he suffered through his many failures, never giving up, because his invention would help people, and finally, through his one success.

He touched the image of his brother's smiling face as he said, "I am satisfied with my care," and found that he didn't really want to stop the tears from coming any longer.

He cried, shedding the emotionless husk that had held him in its grip since Tadashi's death weeks ago.

It's just so unfair. Why… why did he die when Callaghan lived? Why?

There was no answer. He felt like a plaything of the world, thrust around by its forceful currents without rhyme or reason, the senseless death of the best person he had ever known darkening the sky above him.

"Hiro." It was a human voice. Honey Lemon. Her hand gripped his shoulder is what must have been intended as a reassuring gesture, but all he could remember was how she had put the green chip back in. He pushed away her arm.

"Leave me alone," he whispered.

Tadashi had been such a good person, such a good brother.

Why had Callaghan lived?

"Hiro…"

"We're not leaving you."

"Come on, man, talk to us."

The microbots. If he hadn't made them, maybe none of this would've happened.

If Callaghan hadn't stolen them.

"Look, Hiro, we're all upset that –"

He couldn't bear it anymore. He ignored them, walking over to pick up the fallen chest plate armor. After pushing it back into Baymax's suit, he fit the joints of his own suit into the magnetic receptors in the robot's back.

"Baymax," he said, voice hard. "Go."

"Hiro, I –"

"Go," he commanded.

"Wait, Hiro!" Wasabi said urgently. "There's something you need to –"

But Hiro didn't hear, because they were already in the air, thrusters overtaking the sound of any voice he could detect.

Baymax took him to one of the floating windmills, where they had sat before with such carefree joy, before everything had changed. Before they had discovered who was behind the mask.

"Those that suffer a loss require support from friends and loved ones."

The words now, in this context, sounded like a rebuke.

"I know," Hiro snapped. "I just… They don't understand what it's like."

The burning hatred, because Callaghan survived and Tadashi did not.

"Were they not Tadashi's friends as well?" the robot asked, almost as if he truly didn't know.

"They were, but..." Hiro struggled to explain. "It's just not the same." He wasn't their brother.

"Why?"

Hiro gave up.

"You know what," he said gloomily, "why don't you just help me –"

Kill Callaghan.

He cut himself short. The word sent a nervous flutter through his heart. Kill.

That's what revenge means, he realized. To make things right.

It would have been better if neither of them had survived the fire. Then this wouldn't have had to happen.

"Help you do what?" Baymax said, oblivious.

"Nothing," he lied. He knew Baymax wouldn't help him with this.

The robot cocked his head to the side. Hiro decided to revise his statement.

"Oh, just with little things," he said. "You know, things that have absolutely nothing to do with Callaghan."

Hiro would be the one to do the dirty work.

.

.

.

.

His opportunity came surprisingly quickly. Reports of a strange portal-vacuum-thing destroying Krei's newest building had appeared on the news just hours later. He asked Baymax to fly him over there, not mentioning the strong possibility that Callaghan would be there. The portal, after all, was similar to the one that had been in the underground factory.

To his surprise, he found the other science nerds that he had befriended already there, waiting.

"Hiro!" Honey Lemon greeted, albeit less enthusiastically than usual. "You came!"

GoGo didn't even look at him, Wasabi looked concerned, and it was impossible to tell what Fred was thinking with his full body suit covering his face.

"Callaghan's here?" he asked, even though he thought he already knew the answer.

The whole group stiffened. He felt strangely separated from them, not one of them anymore. The camaraderie that they had all shared only the day before only made the feeling more heartbreaking.

He pushed the hurt away, buried it into the depths of his mind where it would remain with all the other broken things.

"Hey, uh," Wasabi broke into the tense silence (or was it really silence with the sound of the machine tearing up the building in the background?), "Should we maybe do something about this?"

He gestured towards Callaghan holding Krei threateningly with Hiro's microbots, the ongoing destruction of the building, and a temporary, unsteady truce was formed.

"Right," Hiro said, looking at the situation analytically. Think of it as a bot fight. Where to hit first? His eyes strayed to the microbots holding the portal together – there. "The microbots aren't structurally strong, even together like this," he said out loud, "if we hit them in one concentrated spot, then they'll break up. Look, Callaghan's got them organized into towers."

They all looked and nodded. They were smart enough to figure out themselves how they would hit the towers.

"Those," he said, pointing to the towers he had noticed earlier, "should be our first target. Minimize the damage, stop the portal from destroying more than it already has." And when the portal falls, Callaghan will be distracted. "After that, we focus on getting Krei out of here."

He didn't mention Callaghan. He knew if he had, they would only be suspicious. This way, they still were suspicious, but at least they wouldn't say anything. They would follow his directions.

"Wasabi, Fred, you take that tower. GoGo and Honey Lemon, that one. Baymax and I will get the last one." He flew off as soon as he was done. He had intentionally taken the furthest of the three for himself so that he could be well on his way to Callaghan before any of them would notice. Besides, it would only take the destruction of two towers to collapse the structure. He would know the strength of the microbots; he had invented them, after all.

So instead of flying all the way to the third tower, he instructed Baymax to head to Callaghan.

"I just realized that we'll probably only need to destroy two of the towers," he told Baymax in way of explanation. "So if the others are already doing that, then we can rescue Krei."

It was a blatant lie. Baymax didn't seem to notice.

They arrived at where Callaghan was holding Krei pinned against a wall.

"Callaghan!" he called out. The professor turned, his face visible with the cranial neurotransmitter resting on his head, mask gone. All the better, because now he could see the face of his enemy.

The hatred, the revulsion, was quick to rise.

"Hiro?" Callaghan looked startled.

"You left him to die," he spat, as if in answer to the professor's unspoken question.

Krei's eyes darted from Callaghan to Hiro. Baymax began flying slower, as if uncertain.

"Hiro," Callaghan said, and he wore such an earnest expression that it made him pause for moment, "If I had known Tadashi was in the building, I would have saved him if I could."

He froze.

Tadashi.

It had been the wrong thing for Callaghan to say. Reminding him again why this man needed to die. Infuriating logic that only roused disgust and a refusal to listen.

The hatred that rose within him then was not the cold, calculating mentality that had embraced him in the factory. This was hot and angry, oil bursting angrily from the hot pan, with indiscriminate beads burning those around him even as the majority charged steadfastly towards its target.

"Baymax," he said quietly, trying to restrain the emotions from bursting into his voice, lest hs intentions be known, "Get Krei."

"What are you doing?" Callaghan asked, his voice harsh.

The robot flew towards Krei. A wall of microbots suddenly stood in between them, but it wasn't an unexpected obstacle.

He detached the magnets from Baymax's armor.

"Baymax, now!" he yelled, as he jumped off his brother's creation and into Callaghan's surprised arms.

It was almost ironic how the man had reflexively caught him, an innate instinct to prevent the death of the one who hated him most.

They teetered for a second, the sudden addition of his weight shaking the pillar that Callaghan stood on. The next moment, however, they were stable, Callaghan's mind automatically compensating for the weight and adjusting the microbots accordingly.

"Hiro, what –" The man looked at him in incomprehension, flinched due to some primordial instinct that told him danger, danger.

His hand slipped into his pocket, a knife resting reassuringly in his hand. He had come prepared.

He stared at his enemy, so close it was almost perversely intimate.

"Why?" he asked fruitlessly. "Why did you survive when Tadashi didn't?"

The man's eyes were very wide now, a wild, panicked look in them.

"I –" Callaghan began.

He heard the microbots rustling, knew of the deception. He didn't give Callaghan the chance, allowed that fury, those burning embers inside him (so painful, yet so right), burst into a raging wildfire, his hand moving on its own to match his anger, his dark intention.

Thud.

Everything collapsed. He was suddenly falling, falling, falling – caught, a steady, hard hand scooping down around his armor to hold him in a steady grip.

He laughed, a hyena laugh of terror and relief. Baymax.

"Hiro –"

The robot's voice crackled off, and he thought that for once, the robot didn't know what to say.

I killed Callaghan, he realized, the fact sinking in. I killed him.

He just didn't know how to feel about that. The fury was suddenly gone, to be left a strange pressure without direction, the remnants of the last coals spent in the flame of the final act. There was no reason, no logic, no hate. A sort of vicious satisfaction, and then…

Shock. He was in shock. The world felt disconnected from him, as if nothing around him was quite real. He looked down at his hands, startled to find that they were covered in red.

"You killed him!" a hysterical voice cried, high-pitched and nasally. Krei. "You – look out!"

Almost surreally, he saw the portal come crashing down from above them, somehow still in one piece even without the supports.

"Baymax," he said numbly, fascinated by the color, the strength of the pull towards the portal. He could feel it, tugging at his arm, his red hands. What was in there? Surely it didn't matter if he just… let himself find out. "Don't dodge."

The robot did dodge, of course. He didn't follow orders if it meant the death or injury of a human being.

So it was that he only watched from the sidelines as Callaghan's body and the microbots were absorbed into the portal.

Huh.

He didn't know how to feel. It wasn't real.

The portal crashed to the ground, a resounding thud, like the knife entering Callaghan's chest, except louder.

Then there was yelling. He heard it through muted glass, both angry, worried, and terrified. A human hand dragged him away, stringing him along, and he helplessly allowed it to. He glanced back, to find Baymax wasn't moving, staring at the portal.

"I'm sensing a female life sign," he said, his arm lifting slowly to point at the portal. "Over there."

The words tore apart the bubble that had encompassed him, the cruel reality cutting past the protective shell that had sheltered him to expose the terrible truth. Sounds were magnified, his vision crystallized, and it was with unadulterated horror that he stared at the events around him.

Destruction. He stared at his hands. The red was blood. On his hands. He had just killed someone.

He felt his heart rate pick up, his breathing quicken and shallow. His dizziness wasn't enough to prevent him from seeing the sickening reality around him.

There's someone alive inside that portal.

Something within him grasped that thought with greedy, clutching hands. Redemption. If he saved this girl, if he saved someone, then that would balance out the act, right? A life for a life?

It was clutching at straws, but he didn't care. He tore his arm away from whoever had been leading him, running back to Baymax and the portal.

"Baymax!" he yelled, voice hoarse. "Take us into the portal! We're going to save her!"

.

.

.

.

.

"... I'm satisfied with my care."

.

.

.

.

.

.

He found himself staring at Tadashi's bed, blank and mute. He hadn't bothered to change from his armor. If Aunt Cass saw it, or even if she had already seen it, he wasn't sure he could bring himself to care about something so trite as getting into trouble for being that "hero" they had seen on TV.

He wondered if he was going to be arrested. No, there was no proof that he had killed Callaghan – he had long since washed the blood from his hands, and there was no body. Besides, Callaghan was already marked deceased, and he doubted Krei would want to bring up the incident if he could help it, from his shell-shocked looks.

There are now two things I'm missing, he thought. Both Tadashi and Baymax. Both stupid heroes.

Both stupid heroes that had died trying to save someone. He had killed someone, and it didn't even bring Tadashi back or give any solace. Only emptiness.

Maybe there's more than just two things.

It was a bitter thought, hard to swallow.

"Hiro?" It was Honey Lemon, dressed in civilian clothes. He wondered how she had known where he lived, and then thought he was stupid for even wondering. Of course, Tadashi had probably told her.

"What?" he muttered.

"I…" She audibly swallowed. "We've been worried about you."

"Don't lie," he said. He doubted the others would care much at all for him, considering what they had seen.

"Well," she conceded, her voice still sounding as if she were walking on broken eggshells, "GoGo was angry. But I think the others understand."

She sat down next to him.

"Why did Aunt Cass let you in?" he asked offhandedly.

"I told her I needed to talk to you about something."

"That easy?" He snorted incredulously. "Why are you really here?"

"I… There really is something we need to tell you." She pulled out a flashdrive. He eyed it curiously.

"What is that?"

"There was… There was more more to the video than what we saw in the factory. Wasabi didn't want to show it to you, but I thought you needed to know."

"Know what?" he asked.

As an answer, she walked to his computer and plugged it in. Moments later, a video appeared on the flashdrive, a continuation of the scene he had seen earlier. This time, Callaghan appeared as soon as the portal experiment had collapsed and the pilot – Abigail, the woman he and Baymax had rescued – supposedly dead. He watched as Callaghan marched over to Krei, his eyes puffy and voice angry and upset. He wondered what it meant.

Honey Lemon rewinded the video and paused at the point when the pilot was entering her craft. She zoomed in on her helmet, the tiny letters that were inscribed into it in black ink.

Callaghan.

He felt as if something had knocked the wind out of him, as he stared at that small label. A niggling, terrible suspicion formed inside of him.

"She was his daughter," Honey Lemon said.

He couldn't speak. Tears sprung into his eyes, as he realized why Callaghan had been holding Krei in his grip that entire time, why he had been so intent on destroying that building. It was the same reason why Hiro had killed the professor.

He felt himself shaking, and Honey Lemon wrapped a reassuring hand around his shoulder. This time, he didn't push it away.

"It'll be okay," she crooned, pulling him into a hug. "Everything will be fine."

The words were lies, but he accepted them nevertheless.

They were the only solace he would have, when he had blood on his hands.