Chapter Summary: Tadashi decides to start a superhero team to catch the masked man.

Disclaimer: I don't own Big Hero 6 and its characters.

Eight Years Ago.

"Ow, it stings!" six-year-old Hiro wailed. His big brother was cleaning his scrapes as the two sat in their bedroom. "Stop, you're making my skin melt!"

"You're exaggerating," eleven-year-old Tadashi said. "If you're a big boy, don't cry over this much."

Hiro pouted. "Says the guy who screams and begs Aunt Cass not to take him to the dentist."

Tadashi rolled his and just laughed while he applied the bandages on Hiro's skin. Then he takes out a small bag of gummy bears and hands it to Hiro.

"Here, Hiro," he said, smiling. "You were noisy, but this is a reward for letting me treat you."

Hiro's eyes shone bright and he happily opens the bag after thanking his brother. Tadashi leaned back as he watched Hiro fill his cheeks with colorful gummy candy. He thought back to the time earlier when he chased away a group of older boys after he caught them kicking Hiro to the ground and teasing him. He felt disgusted, why would someone pick on a little kid like that?

"Hiro, are you really okay?" he asked softly. "Those guys didn't really do anything else to you, did they?"

Hiro became quiet as he chewed his candy slowly. Then he averted his gaze away; his face filled with shame.

"It's nothing, we just had a little fight," the messy-haired boy said quietly.

"Nothing? Hiro, they're bullies!" Tadashi said, putting a hand on his shoulder. "Why are you excusing their actions?"

Hiro flinched away and he gripped the gummy bear pack in his hands. Then he muttered something under his breath and Tadashi had to make him repeat it.

"They called me a nerd because I'm smarter than them," Hiro finally said, his voice sound shaky and broken.

Tadashi stared at him in shock and he felt anger at the boys who hurt Hiro's body and confidence. He pulled Hiro into a hug and rub his back while Hiro's entire body shook.

"They're just jerks, Hiro," he told them kindly. "They don't understand how brilliant you are because you solved a mathematical theorem and you're going to a higher-grade school even though you're pretty young. You're a genius, Hiro, be proud of that. Sure, you'll be taking the same classes with me and along with older kids, but I'll be there to guide you the entire time."

Tadashi became quiet when he saw Hiro still looked sad and unsure. He then gets an idea and pulls up Hiro's shirt without warning.

"Hey, what are you doing-?!" Hiro demanded.

Not replying, Tadashi blew a huge raspberry on Hiro's belly. The little boy burst out laughing and kicked his feet happily as he tried to push his brother away.

"Tadashi, you meanieee! St-stop-ahahaha!" he giggled.

"No way!" Tadashi snickered as he tickled Hiro's sides.

Today.

Tadashi's life flashed before his eyes. He couldn't remember what exactly happened until he noticed the van is quickly filling up with water. He quickly held his breath before he got completely submerged. He blinked through the faintly lit seawater and he found out the car had landed at the bottom of the bay. A horrible thought brought a cold child down his spine: his friends! He saw them struggling to escape from inside the car and he hastily tried to unlock his seatbelt so he can save them. If they die, it's because of his fault. He should have made them leave earlier before he went inside the warehouse. Now they're going to drown because of him.

He felt his head getting lighter and his chest ready to explode. No, he can't die yet! He has to save his friends... His aunt's waiting for him... He needs to catch the masked man...

Then he heard the faint sound of something heavy falling into the sand nearby. He looked around to see Baymax's white hand reaching for him.

Baymax's balloon body, now free of the heavy carbon-fiber armor, burst into the surface of the dark water and bobbed onto his back. The the five college friends cling on too of his stomach, coughing and gasping for air. They were all saved.

"Your injuries require my attention," Baymax told them. "And your body temperatures are low."

Tadashi sighed with relief, seeing all his friends saved in time though his heart is still hammering after their frightening encounter with the masked man. Whoever it was under the Kabuki mask, he came close to killing them. It was a shame he wasn't able to catch him tonight, but at least Tadashi learned some new clues. The robotics student decided to focus on the group's safety before he decides what's the next plan.

"We should get out of here," Tadashi said to the others, his teeth chattering. They need to get warm up as quickly as possible before they catch hypothermia. He notice Fred's face brightening up.

"I know a place," the school mascot said.

Within an hour, Tadashi and his friends were all leaning up against Baymax's warm body while sitting in the middle of Fred's room. The others were shocked to learn that Fred's home is located in the most exclusive suburb of San Fransokyo. Tadashi wasn't surprised since he already knew Fred being secretly rich long before the others did, though he never ventured inside the huge mansion before until now.

"It's like spooning a warm marshmallow~" Fred sighed as lay on top of Baymax's back.

"Hmm, it's making me feel less bad for losing my van," Wasabi agreed, though the mention of his lost car made him sniffled a bit. "How am I going to explain my kid sister that we don't have a car now."

"Hey, I'll help replace it!" Fred suggested. "Besides, that's how I was able to help get some of the materials Tadashi need to build Baymax!"

"... That would explain why Tadashi tolerated you enough to hang out with us," Wasabi muttered. "I thought of a different reason..."

Tadashi had removed all of his carbon-fiber armor and he's now pacing around the room, looking at the picture of the mysterious bird symbol he drew as well as words he read from the papers he remembered from the warehouse. He managed to explain to them his discoveries in the warehouse, including the strange conversation he overheard from the mysterious woman.

"You guys seriously don't know what this symbol and Silent Sparrow means?" Tadashi asked, looking at his friends.

"Tadashi, if we know, we'd tell you," Gogo said as she popped a new bubblegum. "The only thing we know is that Akuma Island, and it's that island located off-coast from this city."

"Well, then... what do we know about Akuma Island?" Tadashi asked, waiting for some answers. His clueless friends looked at each other. They were stumped.

Tadashi sighed and flopped on the couch, running a hand through his damp hair.

"Whoever the masked man is, he's using my brother's microbots and he wants something to do with that island."

"Tadashi," Honey and the others joined him on the couch after they're warmed enough. "Are you really sure this is the same man who started the fire?"

"I know it's him," Tadashi said, clenching the paper tight. "He didn't seem to care if people got hurt or killed as long he got those microbots."

"But there was a lot of people who watched Hiro's demonstration," Wasabi pointed out. "Who would be so desperate to steal his invention?"

"Isn't it obvious?" Fred suddenly spoke up. The was a glint in his eyes.

He dropped various comic books into their hands and began naming off different supervillains and criminals who are secretly millionaires. Then he turned on the giant TV screen to show his number-one suspect for the masked man.

"Our Mister Kabuki Guy is none other than... Alistair Krei!" he exclaimed.

Everyone gaped at him.

"You're kidding!" Wasabi cried, raising an eyebrow.

"He was at the showcase that day, remember?" Fred reminded them. "He wanted to buy the microbots but Hiro turned him down. Now he stole them!"

"That's a good point, Freddie," Honey said. "But... he's kind of high profile, isn't he?"

"And if he's that masked lunatic, why would he need those microbots?" Gogo argued.

"Profit, power, and taking over the world," Fred replied. "I bet he's making a doomsday machine in Akuma Island."

"Fred," Tadashi finally spoke up and he sets down the comic book he just looked over. He walked over to Fred. "While your theory seems plausible, you have to remember not all supervillains are rich guys."

"What are you implying, Tadashi?" Honey inquired.

"The masked man knows how the microbots worked, and how to build them," the inventor said. "If we're going by comic book logic... our masked man has to be a scientist."

"That's where the missing employees comes in!" Fred piped up. "They were engineers who worked for Krei!"

"Wait, Alistair Krei kidnapping his own employees? That doesn't make sense," Wasabi said.

Tadashi became unnaturally silent and expression became cold as he wandered off from the group. Baymax waddled over to him. The inventor noticed his robot's presence and remembered something.

"Baymax, how are your scanners?" he asked. "You said they were damaged?"

"It isn't serious, since I was still able to sense you were in need of my aid earlier," Baymax said. "With some minor fixing, they should be working good as they were before. I deeply apologizing for not scanning the masked man earlier as possible."

Tadashi nodded and patted his arm. "It's alright, buddy. We'll have to figure out something else."

He clutched his head, trying to think hard There is no dead end to this, he has to think of a new angle. ... Hold the phone. Tadashi takes out the petri dish to see the lone microbot. It's moving a little so the masked man is still on the loose.

"I know how to find him!" Tadashi chimed up excitedly. "This microbot is still attracted to the others. It only moves when he's active, but it will lead us to him."

"Hang on," Gogo stopped him. "San Fransokyo is huge, and he could be anywhere. To find him, you'd have to patrol the entire city while relying on one, single nanobot. And that takes, you know, forever."

"I'll just have to duplicate the eletromagnetic schematics so I don't have to rely on a single direction." The gears in Tadashi's head are turning faster with this spark of inspiration. He paused. "He's responsible for Hiro's death, and I have to stop him whatever he's planning."

He looked at his friends expecting them to stop him or tell him he's crazy.

Gogo exchanged glances with the others before standing up. "If you're going to do this, then you're going to need our help," she said.

Tadashi was taken aback, his eyes widen. "Wait, what?"

Fred stood next to her. "How soon do we start finding him?" he asked.

"Hang on, wait a sec..."

Wasabi interrupted him, "We nearly got killed by a man in a Kabuki mask. But if catching him brings Hiro justice, then I'm in."

Honey agreed, nodding. "I mean, we're the only ones who could do it, right?"

"Support from friends is a requirement for the healing process," Baymax stated.

"Listen to me!" Tadashi yelled. "You all nearly died because of I didn't warn you about the danger. You can't do this with me, because it's my responsibility. I'm not..." His tone wavered and he glanced down, looking scared and defeated. "I'm not strong enough to protect all of you."

"You're our best friend, Tadashi," Gogo said, putting a hand on his shoulder which made him turn to her. She gave him a soft, warm look, which he has never seen on her face before. "After Hiro died and you shut yourself away, we never gave up on you. And we're not planning on doing it any time soon."

The others came up and placed their hands on his back.

"Hiro's not only your little brother, but he's one of us," Fred said. "The masked man messes with you, he messes with all of us!"

Tadashi stared at his friends and felt his eyes becoming watery. However, he quickly dried his tears.

"I was such an idiot," he said with a weak smile. "I pushed you away for weeks and here you all are, ready to stand by me."

"It's alright," Wasabi shrugged. "But we still don't know how we can go up against that guy. We're nerds!"

"No," Tadashi said as he stared up a huge picture of a group of superheroes. He remembered his brief stint as Big Heroman. "We can be something more..."

Somewhere in the other side of San Fransokyo, a male engineer expert just ended his shift at a technological lab which is affiliated to Krei Tech Industries. He stepped into his apartment and turned on his laptop for last minute checking of his assignment before heading off to bed.

He didn't notice a shadowy figure moving outside his apartment. With exhausted smile, he turned closed his laptop for the night. Then he felt a cold breeze blowing into the room and he found it odd; he remembered closing his window earlier this morning before leaving for work.

He turned around to see a tall person wearing a Kabuki mask glaring at him at his window. The expert quickly picked up the phone to call the police but the masked person quickly used the microbots to grab him and knock him out. After carrying him outside through the window, the masked man then tossed what looks like a metallic ball into the room at the technician's direction before leaping off. The grenade beeped loudly and glowed...

A huge burst of explosion was set off in the apartment, and the fire department and police was alerted by terrified neighbors. The Kabuki-masked man watch the fire consume the technician's apartment with the unconscious expert being carried by the microbots. He adjusted his mask before he disappeared into the shadows.

The expert slowly awakened but before he can see where he is, he is roughly thrown into a dark, metal room. He groaned in pain and looked up to see he was not alone in the room. He saw about four other people but he recognized them immediately; they all worked on a government project at Akuma Island.

"Moon, are you alright!" A terrified female technician asked him.

"I'm not hurt, but..." Moon shook his head as he sat and moved closer to the others. "Where are we?"

"I don't know," a male engineer said. "But Jones and I have been kidnapped before you after leaving Krei Tech together. Some guy in a Kabuki mask knocked us out and left us here in this room, so we don't know exactly where we are."

"Kabuki mask... Who on earth is he and what does he want from us?!" Moon demanded, trying not to panic.

"You all know perfectly who I am," a voice said behind them. The masked man menacingly approached them, with the microbots moving around his feet and up against the walls. The five scientists scrambled into the corner in fear.

The dark-clothed figure raised the Kabuki mask a bit to reveal his face, and Moon gasped in shock.

"It can't be...!"

"You cannot leave this place," the masked man coldly told them after putting down the mask. "I have... an important job for all of you, and I will make sure it'll be carried out."

"Listen," the expert began. He tried to reason with him but he was trembling all over. "If it's money you want, we can get you some-"

"Be silent or I'll have the microbots inflict pain into your body in ways you don't want to imagine," the masked man snapped harshly. Then he opened the blueprint and showed the scientist what looks like a giant circle of a portal. "If you want to live longer, I suggest you better start using your brains wisely."

"Why are you doing this?" the female technician whimpered.

"Haven't you figured it out already? This is a revenge story."

Tadashi and Baymax took the cable car that leads them to the street where their neighborhood is. Gogo is with them.

"You didn't have to come with me," Tadashi told her as the three walked along the dark, empty street. Baymax is closely following the two behind.

"I'll scram after I see you home," Gogo said, putting his hands in the pocket of her jacket. "Besides, I owe you an apology."

"For what?"

Gogo looked a little embarrassed. "For saying such things last time I was in your room. It was uncalled for and I was hard."

"Well, I'm sorry too for my attitude," Tadashi said sheepishly, rubbing his neck.

Soon they were standing in front of the Lucky Cat cafe. Tadashi coughed and looked at Gogo, trying to think what else to say. For some reason, he felt awkward to be around her and he found himself avoiding her gaze. Yet, he felt strangely giddy at the same time.

"Well... I'll see you and the rest of the guys tomorrow," he said. "We'll discuss our next plan."

Gogo nodded slowly, but she was staring at him. She popped another gum and spoke, "It's so weird to see you not wearing your hat anymore. I kinda like it."

"Really?" Tadashi asked quietly. He found himself smiling.

"It makes you look cooler." Then Gogo crackled the tiniest smiles in her deadpan expression. "Or makes me feel better that you're not going bald underneath."

Tadashi chuckled over the joke while Baymax watch closely, noticing a change in Tadashi's neurotransmitters. Despite the near-death experience that happened earlier, the atmosphere seems lighthearted.

Then without another word, Gogo bowed a little. "Goodnight, Tadashi," she mumbled and then left quickly. Tadashi could have sworn he saw a tiny blush on her face. He wanted to call out after her, but he couldn't find his voice. Instead, he watches her go until she disappears into the next corner. A felt a small, empty longing in his chest.

Baymax approached his creator. "Your heart rate has accelerated," he told him. "And there are an increase levels of dopamine and phenylethylmine, indicating you are experiencing unspoken bliss and infatuation."

Tadashi's face burned in indignation and embarrassment. "Infatuation?! To that radish-legged midget who drives like a maniac? Have you lost your mind?!"

"I cannot lose my mind, I am a robot," Baymax replied.

Tadashi shook his head and opened the door to the cafe, muttering under his breath.

"Ridiculous. I have no time for infatuation, I got a psycho to catch..."

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Notes: There'll be more backstory sequences for the Hamabros later into the story. Just a little warning. XD

Oh, while this story will focus on the themes of loss, grief, and revenge; there's gonna be some mild romantic moments though they won't overtake the story since Tadashi's still hurting and isn't ready to seek a relationship until his mission is over. Plus, it's kinda fun to write Tadashi being all tsundere.