This should have been a routine mission. When teen genius Hiro Hamada got an alert on his phone telling him that one of the sensors he'd installed on Akuma Island had picked up on some unusual activity, he figured that it must be malfunctioning or that maybe it was a case of a wild animal getting in and messing with the tech. At this points the sensors were more of a memorial than anything-there hadn't been any activity from either of those portals since… Well, since right after the Expo fire. When he'd placed them on the island after the battle between Big Hero 6 (the newly formed superhero group that Hiro was now the leader of) and Yokai (the masked villain who had been responsible for the death of Hiro's beloved older brother, Tadashi), it had been to make sure that no one else attempted to use the technology for ill purposes like Yokai had. Still, considering no one had even touched the island for almost three years, Hiro honestly didn't believe that someone was going to start now, especially not with Yokai safely locked in prison.

All the same, some nagging suspicion told him that he should probably check it out, just to be safe, and so, with a sigh of irritation at being pulled away from his latest project, he heads over to activate Baymax, the nursebot that Tadashi had built before his death as a prototype for the line of medical robots he dreamed of releasing to drastically improve the current healthcare system (and, on a less professional level, to be a companion for his majorly antisocial younger brother.) Hiro had upgraded the robot's design slightly and created armor for it right after the fire to turn it into a crime fighting machine in order to help him find his brother's killer. After everything they'd been through together, Baymax had become one of his closest friends, and during superhero missions the robot also doubled as his ride to get from place to place, as well as being something of a bodyguard for him (although in recent years Hiro had developed his own form of self defense using an invention of his own that he called "microbots" so that he didn't have to be so dependent on his marshmallow-esque companion.).

"Hello, Hiro," Baymax greets the teen in a friendly robotic chirp when he finishes inflating from the compact red case where he usually stayed when he was not needed for anything. "What may I do to help assist you?"

"We've got an irregular signal coming from one of the sensors on Akuma island," Hiro explains, smiling slightly at the robot's perpetually cheerful sounding voice. "It's probably nothing, but think you can give me a lift?"

"Of course," Baymax answers, his robotic eyes squinting up ever so slightly at the corners in his own unique version of a smile.

"Awesome! Thanks, buddy!" Hiro grins up at him. "Let's get armored up and then go check this out-the sooner it turns out to be nothing, the sooner we can get back here!"

Within minutes the two were in their full superhero gear and flying over downtown San Fransokyo towards the island. It was a beautiful day out-if it weren't for this odd feeling in the pit of his stomach that something really was wrong at the island, Hiro probably would have been absolutely exhilarated by the flight (despite the fact that he'd been riding around on Baymax's back for years, this never got old.) Oh well-the sooner he got to the island and proved to himself that it was nothing, the sooner they could get out of there. With any luck, maybe he and Baymax might even have enough time for a nice, relaxing fly-over of the city before heading back to the lab at SFIT to get back to work.

Ten minutes later the two come in for a landing on the old, deserted island that had once been the site of an experimental portal that was supposed to have revolutionized the travel industry. Instead the portals had become unstable during the first test and had had to be shut down, trapping the test pilot-Yokai's daughter- inside. It had been that accident that had led Yokai down the dark path, wanting revenge on Alistair Krei, the man who had pushed the experiment to go forward despite knowing the potential risks. To exact his revenge, Yokai had not only stolen Hiro's microbots, but he had set fire to the entire Expo hall in order to fake his own death and cover his tracks. Tadashi, the pure soul that he was, had rushed into the building to try to save the man and had died in the attempt. Honestly, being back here on this island brought up a lot of painful memories for Hiro, and he was going to be all too happy to get out of here as soon as possible.

"Are you alright?" Baymax asks, his scanner picking up signs of distress from the young man.

"Yeah, fine," Hiro answers, brushing aside his concerns. "Let's just get this over with."

"All right," Baymax agrees, apparently deciding that arguing with his charge wouldn't actually do either of them any good.

"It looks like the sensor that got set off is in the portal room," Hiro notes, checking his phone for confirmation and frowning when he sees that several other sensors had since been triggered off. "What the heck?" he quietly mutters. Okay, so maybe this was a bigger deal than he'd originally thought. The logical part of his brain says that he should probably call for backup and wait for the others to get here before going to check it out. But, as usual, his insatiable curiosity overpowered his common sense-if he waited, whatever was causing this might have already disappeared! Besides, he had Baymax with him and he was probably the strongest member on the team, so he should be perfectly safe, right?

"C'mon, let's go!" Hiro waves to the robot before hurrying off down the hallway, the nursebot quickly waddling after him.

Once they reach the panel in the wall that leads into the portal room, Hiro pushes it open with Baymax's help and hurries inside to see if he could find the source of the disturbance that was setting his sensors off. It didn't take long for him to locate it.

"Whoa…" he quietly gasps when he looks down into the part of the room where the remains of the portals still stood. Hovering just above the fractured structure of the one on the left was some sort of weird glowing shape-blue and crackling with some sort of energy, the closest thing Hiro could describe it as was a literal tear in space: it was as if the air was a canvas and someone had ripped a small hole right through it.

"C'mon, we've got to check this out!" Hiro cries, curiosity again getting the better of him as he heads down to the main floor to investigate.

"Hiro, please exercise caution!" Baymax warns him, hurrying after him and doing his best to keep up.

"C'mon, Bay!" Hiro laughs, grinning teasingly back at his robotic companion as he hurries forward.

About five feet away from the glowing tear, he finally forces himself to slow down-as curious as he was, he didn't know exactly what this thing could do and he didn't want to go getting himself seriously injured or worse. Even at this distance, though, he could feel some sort of pull on his body from it-it was like the tear, whatever it was, had it's own field of gravity and wanted to suck him in, although at this distance it wasn't exerting a strong enough pull that it could actually pose him any real danger. Glancing down at the floor, he notices that little bits of dust and dirt seemed to be being quietly sucked into the tear like it was some sort of mini vacuum.

He was just leaning down to study the phenomena at a closer range when Baymax finally caught up with him, calling out his name. Hiro, caught off guard and already in an awkward position, found himself losing his balance and falling forward. Taking advantage of his closeness and inability to resist its pull, the tear's gravitational field quickly, almost gleefully, grabs hold of him and, before he can even cry out in an alarm, he's sucked in.

For a brief couple of seconds, there's the flash of bright pink and blue lights and the feeling of cold. And then suddenly things weren't cold anymore-in fact, they were the exact opposite of cold. Gasping as he's unceremoniously dumped out onto a hard concrete floor, Hiro looks around at his surroundings and realizes with quiet horror that he's currently inside a burning building. Instantly the young man takes stock of his situation-he had no idea where he was, but he needed to get out of here, now. He could try to escape from the building, but what would he find outside of the building? Turning back around, he sees that there's an identical tear to the one he'd seen back on Akuma Island behind him. Well, if going through one tear could send him here, it stood to reason that going back through it would send him back to where he'd been-or, at least, he hoped it would. Any chance of getting back was better than staying here, so he readies himself to jump back into the portal. But just before he can, he suddenly becomes aware of a voice-weak, but still definitely there, calling out for help. Hiro stiffens. As much as he wanted to get back home, if someone was in danger and there was something he could do about it, it was his responsibility to help. He glances back at the portal-it was still definitely there, but was it imagination or was it slightly smaller now? He was torn by indecision-if the portal was getting smaller, what if by the time he got back it was gone? What if it was his only way home? What would his family and friends do if he disappeared without an explanation? After losing Tadashi, would they be able to survive losing him too?

But there was someone trapped in this burning building-trapped like Tadashi had been. How could he live with himself if he went back home and left this poor soul to die? He wouldn't be able to live with himself, and he knew it. Besides, if he was fast enough, then maybe he'd still have time to get back here before the portal closed.

Making sure that his visor is firmly down to prevent him from breathing in any of the ash and smoke, Hiro takes off in the direction of the voice he'd heard-it was weak, but still there.

"I'm coming!" Hiro calls, using the speaker inside his helmet to amplify his voice. "Where are you?"

"Here!" the voice from earlier calls, the answer quickly followed by rasping coughs. "I-I'm trapped!"

"Hold on, I'm coming!" Hiro shouts, feeling his heart racing in his chest-at this point he knew that he had to save this guy, no matter what.

"P-Please, hurry!" the voice says, weaker this time and punctuated yet again by loud coughing.

"I'm coming! Don't give up!" Hiro answers, eyes desperately scanning the wreckage for any sign of the trapped man. Come on, come on, he needed a sign, anything-!

There!

He finally catches sight of what looked like a human being, trapped under a large wooden support beam. Parts of the man's clothing were smouldering, although it looked like the fire hadn't quite reached him yet-still, he was probably only seconds away from actually going up in flames.

Adrenaline coursing through his veins, Hiro races through the building and over to the man. Smoke was clouding his vision and making it hard to see, but the teen superhero was at least able to make out the general shape of things. Hopefully that would be enough. The first thing he needed to do was get this beam off of this guy-Baymax would have been able to do it no problem, but the nursebot wasn't here. Maybe the microbots could do it, though-

Wait, the microbots! Those could buy them some extra time! Hadn't Yokai (then Professor Callaghan) used the microbots to escape the fire? Maybe they could actually be put to good use for once! Releasing a stream of the tiny robots from his backpack, Hiro quickly forms a protective bubble around himself, the man, and the part of the beam directly in front of them before setting to work on removing it. The guy wasn't talking and that had Hiro worried that maybe he was already too late, but a glance downward told him that the man was still definitely breathing. The tiny bit the teen could see of the guy's expression in the glow of his suit indicated that he was in a lot of pain, but he was at least still breathing.

"Don't worry, we're going to get you out of here," Hiro promises, using the microbots to slowly and carefully lift the beam up until it was fully off of the other man. Once it was a safe distance away, he tosses it and then quickly closes the bubble fully around them. Now they just needed to concentrate on finding a way out of this building! Facing with this task, however, Hiro had to wonder how the heck Callaghan had managed to move in this thing-there was no visibility through the thick protective layer of bots!

"Can you walk?" Hiro finally asks the guy who was still lying gasping at his feet.

"I-I don't know," the man answers, voice choked with pain. "That beam…"

"Damn," Hiro quietly growls-so much for both of them just walking out of here. All right, well, his suit was fireproof (after what had happened to Tadashi, he'd made sure that all of the team's suits were)-maybe if he created something out of the microbots to carry the guy, then he could walk them out of here.

"Okay, I'm going to try something, just stay calm and don't move, okay?" the teen genius finally says.

"Don't think I'm exactly capable of movement at the moment, so I'll just work on the staying calm part," the other man returns, wry humor making its way into his voice despite the fact that he was obviously in major pain. Something about it made Hiro think of the way Tadashi had always tried to make jokes when he was hurting to try keep anyone from being actually worried about him-honestly, the guy's voice even sounded a little bit like Tadashi's…

W-Wait a minute!

Hiro's eyes go wide as suddenly all of the little pieces of the puzzle that he'd been ignoring up 'til this point start to come together. The fire; the way that the building they were in looked a lot like the Expo Hall; the way that this man talked and acted so much like his deceased nii-chan…

"T-Tadashi?" Hiro whispers as the realization finally dawns on him.

"H-How do you know my name?" the other guy asks, tone confused and a bit frightened. But before he could ask any further questions, he goes into another intense coughing fit.

Shit, shit, shit, shit! Hiro was honestly panicking at this point-as much as he should be overjoyed to see his elder sibling again, the circumstances for the reunion were less than idea, especially considering it seemed like he had just inadvertently prevented Tadashi's death. Technically this was a good thing-he could just take Tadashi outside, return him to his family, and prevent himself from ever having to go through the pain of losing his brother. But there were so many other factors to take into account-if Tadashi had lived, Big Hero 6 probably never would have formed. If Big Hero 6 hadn't formed, Yokai and countless other villains would never have been stopped. So many things had happened that had been set in motion by Tadashi's death, and there was some major danger in messing with the time stream like this. On the other hand, Hiro couldn't bring himself to leave his brother for dead-to almost save him and then abandon him like Callaghan had would be messed up beyond words. Beyond that, now that he had him back, Hiro knew that he wasn't going to be able to let his nii-chan go again. He just couldn't. So there was only one option-as stupid and potentially dangerous as it sounded, he was going to have to take Tadashi back to the future with him. That is, provided the portal was actually still open.

Panic filling his chest at the realization that they might be too late, Hiro forces himself to shove away all his concerns about the possible dangers of bringing his brother to the future as well as the slight glee that came with the idea of actually having his nii-chan back. First he had to get them out of here, then he could think about the consequences.

"Okay, j-just hold tight," Hiro instructs the other man, heart clenching with fear at just how weak Tadashi was looking-no, he was so close to saving him, he couldn't lose him again!

"'K-Kay," Tadashi agrees, not even having the strength to question him.

"I-I'm going to get us out of here. I promise," Hiro says softly, allowing his eyes to drink in the sight of his brother one last time, just in case he ended up being too late, before creating a hole in the bubble and climbing out.

Outside the protective sphere, things had gotten worse-a lot worse. The fire was almost completely surrounding them and there was debris everywhere. Still, Hiro had found himself in tighter spots before, and, besides, this time he had another life depending on him-his nii-chan's life-and he was going to do everything in his power to save them both.

Directing the microbots to stay in a bubble around Tadashi and carefully carry him along behind him, the teen superhero starts making his way through the burning Expo hall. He had a pretty good idea as to where the portal had been, but he could only pray that it was still open or else they were probably both done for. About a minute later, he finally spots it-it was dangerously small, but it was still there and so there was hope! At this point he's practically sprinting, doing his best to keep the bubble from jarring its poor injured occupant but more concerned with getting them out of here alive than making the ride completely painless-he hated the idea of his nii-chan suffering any more than he already was, but sacrifices had to be made in the name of survival!

His heart was rising in his chest as he gets within a few yards of the portal-they were almost out, they were going to make it! But then suddenly he hears a horrible cracking sound and looks up to see a beam just above them starting to fall towards the ground. If he dodged out of the way, the beam would most likely miss them, but there wouldn't be enough time to get through the portal. He has to make a split second decision-play it safe and be stuck here or risk it all and potentially lose everything. It was a good thing Hiro wasn't a gambler because he always went all in. Putting on an extra burst of speed and making sure that he had a firm hold on the microbot bubble, he leaps for the portal and-

"Oof!" Hiro lets out a low groan as he lands on the hard concrete, back in the portal test chamber on Akuma Island. His entire body ached and his lungs were burning from the smoke that had gotten in despite his protective helmet. But his own pain didn't matter-what mattered right now was finding out if Tadashi had made it! Stumbling to his feet and ignoring the shooting pain in his right knee-he was pretty sure he'd busted it open with this last landing-he staggers over to the microbot bubble, dissolving it as he walks, almost afraid see what was inside. For a moment his heart stops in his chest when he sees no movement from the older man, afraid that he had been too late for the second time in his life. But then he sees his brother's chest rising and falling-it was almost imperceptible, but he was still breathing, which meant he was alive! Hiro could have cried from relief, and he wanted nothing more than to throw his arms around his older sibling, to hug him tight and never let him go. But right now wasn't the time for that-if he wanted to make sure that Tadashi made it, his older brother needed some medical attention, and fast. Fortunately for both of them, they had the world's best nursebot on the case.

As if summoned by Hiro's thoughts, the robot appears by the teen's side.

"Hiro!" Despite the fact that his robotic voice couldn't show much emotion, Hiro could hear the relief in Baymax's tone. Moments later the relief is followed by the closest thing the robot had ever shown to shock. "Tadashi!"

Hiro could understand the nurse bot's reaction to seeing his supposedly deceased creator-the teen genius was honestly still trying to wrap his own head around all of this. But now wasn't the time for questions-it was the time for action.

"Baymax, he's hurt! Can you get him back to the lab?" Hiro asks the robot, his concern and even panic making its way into his voice. Technically they probably should have been heading to the nearest hospital, but right now he didn't trust his brother's safety to anyone but the nurse bot he'd seen time and time again pull medical miracles in the direst of situations when missions had gone awry.

"Of course," Baymax answers, apparently understanding exactly what Hiro was thinking. Carefully-tenderly, almost-he picks up his creator's limp form and cradles it in his arms, heading towards the door. Hiro quickly tags along behind him, praying with each breath that they'd manage to get Tadashi stable in time.