This starts five years after the events of Big Hero 6.

Chapter One: How to Catch a Moving Train

A wise scholar once said that, "When endlessly repeated, the fantastic will inevitably become the mundane."

While plummeting towards the Earth from thousands of feet, Hiro Hamada thought that the wise scholar was a complete and utter moron. While he had now been doing this sort of thing for five years now, each flight was as exhilarating as the first time he had gone airborne.

Just before making contact with the ground Baymax pulled up alongside the speeding train that they were chasing, practically inches from becoming a smudge on the Californian landscape. Cruising at a steady three hundred miles an hour the Cross Continental monorail sped across the green countryside.

"Nice work, buddy," he said fondly, patting the robot's metallic body armour. Suddenly his headset receiver crackled.

"Hiro, this is GoGo. Where are you?"

"Right alongside the train," he replied, "How are you doing?"

"I'm keeping on top of things."

~o~O~o~

"I'm keeping on top of things."

Ha ha, GoGo, real funny. What a great time to develop a sense of humour.

Hanging onto the roof of the speeding monorail's front carriage was the yellow armoured form of GoGo Tomago, doing everything to stop herself from being flung into the air.

"Any word on the others?" Hiro asked through her headset radio.

"All long range signals are jammed," she replied through gritted teeth, "Can't get through to 'em. It's just you and me today."

"I am also present, Miss Tomago," While often claiming that, as a robot, it was impossible for him to be offended, Baymax sounded almost hurt.

"Sorry, Baymax," she said quickly, "You're here too."

"I am aware of that."

"GoGo," Hiro interrupted, "Is there an access patch or anything like that you can use to get inside?"

"Yeah I can see one," she replied, forcing herself forward inch by inch, crawling across, "But they said they'd start killing hostages if they saw anyone."

"Then don't let them see you. Duh. Hiro out."

"Cheeky bastard," she muttered, smirking despite herself.

"You know that I can still hear you, right?"

"Shut up. I know that."

~o~O~o~

Forty-seven minutes before, the Cross Continental monorail had been hijacked on transit by thirteen armed men and women. They immediately took all ninety-three passengers hostage and informed the authorities that if twenty-five million dollars in cash was not delivered to them by the time they pulled into San Fransokyo, they would kill every passenger on board.

Naturally Hiro, GoGo and Baymax were not huge fans of the proposed arrangement and had elected to do something about it.

~o~O~o~

As carefully and silently as possible, GoGo opened the access hatch and jumped down into the train's interior.

Good, there was no-one to be seen, either gunman or hostage. She crept along the hallway before ducking into a nearby compartment. "Baymax," she whispered into her headset, "I need you to scan the train and tell me where they're keeping the hostages. If we can take out the men guarding them we can end this thing right now."

"Scan complete," the robot replied, "The greatest concentration of people is in the dining carriage, two carriages down from your position."

"They should have had them scattered all throughout the train," she said, "That would have been the smart thing, it would have made it more risky for anyone planning a rescue."

"Do you really want to start giving them tactical advice, GoGo?" Hiro snarked.

"Shut up," she said to him for the second time that day, "Where are you?"

"Baymax and I snuck in through the back," he replied, "We'll go forward and meet you in the middle and then come up with more of a plan."

"Sounds good," she agreed. She leant her head out of the compartment door before quickly ducking back in. She could see two black armoured figures enter her carriage, each carrying a strange looking gun.

Okay, I'm going to have to do this fast.

Attaching the wheels to her wrists and ankles, she silently rolled across the floor after the pair before rising to her feet and tapping the nearest hijacker on the shoulder.

"Hi," she said calmly as they turned to face her, "I suppose asking for directions to the loo would be a step to far, right?" Before they could respond, she decked them both in their faces with her spinning wheels, knocking them out cold. "Morons," she muttered under her breath before continuing on her way.

"Are you alright?" Hiro asked, "Baymax said that there were some guys in your carriage."

"They just wanted to know if I was free to hang out later," she replied glibly.

"Did you let 'em down gently?"

"Oh suuuure,"she said sarcastically, "I was very considerate, charming, the whole bundle. I'm a very classy girl, you know that."

"That's news to me."

"Shut up."

~o~O~o~

"Are you and Miss Tomago undergoing social hostilities, Hiro?" Baymax asked as they passed through the cargo carriage.

"No," Hiro replied quickly, "Why do you ask?"

"Because she has told you to shut up on no less than four separate occasions within the past ten minutes." The nineteen year old laughed.

"It's just an expression, mate," he said, grinning at the robot. Even after all these years he was still constantly amazed by his friend's naiveté when it came to human interaction.

"Very well," said Baymax, "I will archive this form of human interaction for later analysis."

"Whatever floats your boat."

"I am capable of floating without need of a vessel such as a boat."

"It's just a… Oh never mind, I'm saying that way too much as it is anyway. It's practically a catchphrase at this point. Here we are."

~o~O~o~

"GoGo," Hiro said, "We've made it to the dining carriage. Where are you?"

"One carriage down from you," she replied, "Baymax, how many guys are guarding the hostages?"

"Approximately nine," the robot answered immediately.

"Approximately?" she asked, "That doesn't sound all that definite."

"Given that I lack the specific medical information for every person on this train it is impossible to differentiate between the hostages and hostage takers," Baymax said apologetically, "However, given that there are two bio-signs in the cockpit (one for the driver and one for the criminal) and two unconscious several carriages behind you, I am confident that my hypothesis is correct. However, I must point out that the device that is currently jamming our long range communications could potentially cause my instruments to make a false reading."

"Fair enough," she said, stopping at the door to the dining carriage, "Alright, I'm here." She ducked underneath the window on the door.

"What do you see?" Hiro asked.

"They've got all of the passengers on the floor," she answered, looking out, "Packed together like sardines, if we screw this up a lot of them could die."

"Then we won't screw it up," came the reply, "Where are the gunmen positioned?"

"Can't you see anything?"

"We're in the cargo compartment," he said, "There's no window on our door."

"There is two gunmen right outside my door," she whispered, "Hang on, just let me take another look… Yep, two on my door, three at yours and there's also two in the middle of the floor. This isn't gonna be easy. We'll have to take 'em all down at once before they can hurt the hostages. Hang on, how strong is the grip in your suit."

"Pretty strong. Why? I'm not gonna like this plan, am I?"

"Probably not," she replied smoothly, "But for some reason your discomfort is a cross I'm willing to bear."

"Why do I put up with you?"

"You just do."

"Fair enough, what's the plan?"

"Punch a hole in the roof and climb up out on top," she instructed, "Baymax will tell you when you're right on top of them, then kick down and take them out on my signal."

"That'll actually work," he said, "Of course you realise that your plan involves me scurrying across the roof of a train going at a respectable fraction of the speed of sound? Why can't Baymax do it?"

"Because there's three guys at your door," she said, " They all have weird guns and to be perfectly honest, I'd rather have Baymax take three and you take two."

"Are you suggesting that I can't take on three heavily armed men?"

"Yes."

"Fair enough."

~o~O~o~

"Fair enough, my ass," Hiro muttered as he climbed out of the newly broken window.

"Be careful, Hiro," Baymax cautioned, "Even with your body armour, a fall from this height and at this speed could potentially cause you a serious injury, possibly even a fatal one."

"I'll be fine," he assured the robot, "See? No problem." He hoisted himself out and up onto the roof. "Okay, buddy," he said into his microphone, "You're gonna need to be my eyes here. How far forward do I go?"

"Stand in the middle of the carriage," the robot instructed, "Now move forward until I tell you to stop." He crawled forward, inch by inch until he heard, "Stop, you are directly on top of them."

"If I come through the roof is there any chance of hitting a passenger?" he asked.

"No," Baymax replied, "There is a space of one point five metres between the gunmen and the nearest hostage."

"Good to know," Hiro said, hitting a button on his wrist guard. A small compartment slid open to reveal a bright pink spherical blob. "Thank you, Honey-Lemon," he said fondly, "Alright, guys, I'm all ready to go, what about you?"

"Ready when you are, kid."

"I am ready, Hiro."

"Alright, let's do this."

~o~O~o~

"Alright, let's do this," said Hiro, through GoGo's radio. She moved to the other end of her carriage, turning the hall into a makeshift runway as she crouched. "We go on Baymax's signal. Count us down, buddy."

"Affirmative.

"Five,

"Four,

"Three,

"Two,

"One,

"Now!"

In less than two seconds, GoGo crossed the length of the entire carriage and leapt through the window, shattering it and piling into the two armed men. She looked up just in time to see a portion of the roof dissolve into a pink powdery cloud that Hiro fell through, landing on his two gunmen and slamming their faces into the floor.

While there was a certain impressive theatricality to the methods that the two humans used to dispatch their foes the elegant practicality of Baymax put them both to shame.

He simply punched through the door and delivered the armed men non-lethal electric shocks via the defibrillators in his hands.

"I always feel very superfluous whenever he's around," Hiro said dejectedly, "He makes it look so easy."

"Whine later," GoGo said quickly, "We've still got to get to the driver and make sure that he's alright. Baymax, watch these guys and look after the passengers."

"Affirmative," replied the robot before turning to face the still huddled passengers. "Please remain calm," he said in his soothing synthetic voice, "The situation is in good hands."

~o~O~o~

"What did you mean when you said that they had weird guns?" Hiro asked as he and GoGo ran down to the driver's compartment, "I didn't take that close of a look at them."

"I couldn't see any ammo mags on them," she said, "And there's some odd light things on the barrel. I'll get Wasabi to take a look at one once this I all over and –" She was suddenly cut off as Hiro tackled her into the nearest compartment just in time to avoid a sudden stream of blinding electricity.

"I'm starting to agree that there's something strange about those guns," he said distractedly. While it was very clearly the wrong time to be having suck thoughts, he couldn't help but notice that their faces were awfully close to one another. She pushed him off of her and stuck her head out before quickly pulling it back to dodge another blast of energy.

"What's he doing?" Hiro asked, crouching behind her.

"She is just guarding the door to the driver," GoGo replied. "Okay, I'm gonna see if I can get to the compartment opposite us."

"GoGo, wait!" Hiro cried out but to no avail, the biker girl had already barrel rolled out through the hallway and into the opposite compartment, narrowly avoiding a third blast of electricity.

"What was that?" she called out, grinning cheekily at him, "I couldn't hear your concern for me over just how awesome that was."

"Shut up," he replied, "Damn it, now you've got me saying it. So what's the plan? One-two?"

"Sounds good," she called back, "You can be the One."

"You just want me to go out there first so that I can get a big old face of lightning don't you?" he asked sarcastically.

"Aw, come on," she faux-crooned, the grin never leaving her face, "Where's your sense of chivalry? You're the big strong man and I'm just the small woman." Hiro knew from experience that GoGo would never ever say something like that unless she really felt like screwing with him. However, if she wanted to play that game, he was more than happy to oblige her.

"I'm not a big strong man," he called out, "You're just really tiny. Anyone looks big next to you."

"I'm gonna get you for that," she said dryly.

"Hey!" called out the woman with the lightning gun, "Are you going to fight or are you going to keep flirting?"

"Hang on," said Hiro, briefly looking out at her, "We're not flirting, this – this isn't flirting, we're just friends… Ah, forget it." He rolled out into the hall and then into the compartment next to GoGo's, a trail of lightning following him just as GoGo leapt out and hurled one of her wheels like a Frisbee out towards the woman, catching her straight in the chest and hurling her to the floor. Before she could regain her footing, Hiro tackled her and pinned her down.

"Do you two need a room?" GoGo asked, her right eyebrow raised high in amusement.

"Oh shut up and help me cuff her," he replied.

I'm never taking the train again, he thought as GoGo smirked innocently at him.

~o~O~o~

One hour later

Looking down from the roof of nearest building, Hiro, GoGo and Baymax watched as the San Fransokyo police department haul away the hijackers and provide aid to the passengers. The sun was beginning its decent over the bay and the sky was awash with orange, blue and purple. Despite being strictly a science nerd that cared only about if something was practical or not, Hiro found himself really enjoying the sight for once.

"We did a good job guys," he said, grinning as the woman leading the attack was forced into the backseat of a police car before being driven away to lockup.

"That we did," GoGo agreed, rubbing Baymax's armoured side affectionately, "You did good in there, big guy. You even managed to pick this loser's slack."

"Hey," Hiro said, trying (and failing miserably) to sound offended before a smile crept out over his face. "Do you think the others are going to be mad they missed this one?" he asked.

"Wasabi and Honey, no," she said before grinning vindictively, "But Fred is gonna crushed. High speed train hijacks are apparently a beloved staple in those comics of his."

"Oh boy, he's gonna throw a hissy fit," Hiro agreed, smiling as they both took in the sunset.

After about forty seconds they both realised that the silence was now becoming somewhat awkward.

"So…" he said, shifting from foot to foot.

"Yeah," she said in the same tone of voice, "It's getting late, I should probably head off and… You know… Later, dude." She punctuated the last word by punching him lightly on the shoulder before turning around and walking away.

"Hiro," Baymax, "Are you alright? I noticed a significant increase in your heartbeat."

"Yeah," said Hiro before swallowing, "Everything's fine."

~o~O~o~

I hope you enjoyed this first chapter. If you thought that the train thing was a little generic, don't worry, I just wanted to use a comic book staple for an action open, kind of like how Skyfall started (without the friendly fire though).

Also, about the characters' first names (non-nicknames):

While in the comics, the characters are all Japanese and have appropriately Japanese names, the cast for the movie had more ethnic variety. So, I was wondering that in cases when a first name would be needed (legal documents, official business, extremely dramatic scenes etc.) if it would bother anyone if I just used the voice actors' first names. For example, GoGo's first name would be Jamie for Jamie Chung. Let me know what you think about that in the comments.

Please leave a review and I'll see you next time.