The world was ending. Nobody knew it yet, but it was up to Casey to save it. And he was lost in the middle of a very -very- crowded New York City. And Casey was starting to realize he might be crowd claustrophobic.

Great.

Casey weaved through the crowd, constantly ducking and backtracking to avoid running into anyone, until he reached an alley. He huffed out a breath and glanced down, his mind flashing back to what he'd left behind.

Was there even anything left behind? The last base had been uncovered, Casey had seen Master Michelangelo just… disintegrate, and Sensei Leonardo…

If Casey closed his eyes, he could still see the glow of red rushing toward them. Casey had just wanted one last hug before he left forever, but the Kraang mech had suddenly come upon them, its laser firing in a split-second. He could almost feel the boiling hot air in his lungs, taste the smoke of destruction…

Casey shouldn't have survived. He didn't know how he had, really, except Sensei must have moved faster than the laser, somehow. Casey distinctly remembered the sensation of falling, then the next thing he knew, he was flat on his back staring at a black sky full of stars and surrounded by people who didn't seem to notice or care that Casey had just fallen out of a portal in their midst.

Casey shook his head and told himself to focus, to not waste Sensei and Master Michelangelo's sacrifice. Sensei had told him to find the key, stop the Kraang. Sure, easy.

Casey lifted the picture and stared at the crude drawing, committing the image of the key to memory. Then he turned the picture around.

The whole family looked so young to Casey. He wondered if the picture was from the time that Master Michelangelo had sent him. Sensei had said before that the picture was his last happy, untainted memory, as it had been taken the day before the invasion.

Would Master Michelangelo send Casey to the time so close to the Kraang's attack? Had he even known when exactly the portal would open?

Casey looked at everyone outside the alley. He could figure out when exactly he was, once he figured out where he was supposed to go. Because Casey suddenly realized that he had no idea where his uncles had lived before the invasion. New York had always been too dangerous in Casey's life for a tour.

Could he ask? Except Casey hadn't seen any yokai in the crowd, so asking about four turtle yokai wouldn't get him anywhere.

Four…

A lump rose in Casey's throat at the thought of seeing the brothers all together again. He didn't even care right then that they wouldn't know who he was!

Casey swallowed the lump and made himself focus on the details of the picture. Sensei wouldn't have sent him into this mission blind. He had an objective, and Sensei had to have made sure Casey would have the clues he needed to find his past self.

They lived underground, Casey knew. They did go outside, but in disguises Master Michelangelo had assured Casey were pretty obvious. If they weren't in disguise, then they were… on the rooftops!

Casey aimed his grapnel for a fire escape halfway up the building wall. It attached and yanked Casey into the air. He disengaged the grapnel as he passed, then caught another fire escape to whip himself onto the roof. He landed in a controlled tumble that ended under a wooden table.

Casey remained still for a few minutes out of habit, then remembered Kraang didn't patrol these skies yet. He quickly crawled out and stood.

For the briefest instant, Casey was glad he was alone. But the thought was gone as quickly as it had come. He'd much rather have rolled into his uncles' midst and have them laugh at his caution than to find himself still very much alone.

Casey again forced himself to focus. The skies and rooftops as far as Casey could see were completely empty.

Where did he even begin? The city unrolled before him like a scroll, and much of it was hidden by buildings taller than where Casey stood. Below, the streets were full of people and vehicles.

"Have to start somewhere," Casey told himself.

Casey put down his mask and held up the picture. The mask automatically recorded everything Casey saw, so all he had to do was turn on facial recognition. If he passed any of his family in the street, the mask would alert him.

Casey looked down. With nobody else in the sky, Casey had a feeling that he'd grab a lot of attention if he started swinging around. Maybe it would be fine, but Casey didn't want to cause some sort of disturbance that would delay his search. Plus, he'd be more likely to miss something from high above.

Casey eyed the crowd skeptically, but safely stowed the picture inside his cowl and climbed down regardless. He'd faced Kraang, for crying out loud, he wasn't going to let a bunch of people scare him off.

Nobody else was wearing a mask like Casey, but nobody seemed to care about Casey's, for which he was glad. He had his hands full making sure he didn't bump into anyone.

The crowd Casey had been weaving through suddenly stopped. Reflexively, Casey did the same, gaze shooting toward the sky.

Nothing.

A moment later, the crowd started moving again. Casey mentally shrugged and kept going.

Except it happened again.

By the third time, Casey was starting to put the pieces together. Casey knew about roads and sidewalks, and he noticed that people in the past didn't normally walk on the streets.

Uncle Raph had told him about not walking on roads once. It had always made sense because the streets were open and more visible to Kraang, but it was also because in the past, vehicles stayed on the road. Which was strange because people could dodge vehicles just as easily as people.

Anyway, if they were crossing from one sidewalk to another across the street, there were specially marked sections of road where cars stopped at regular intervals so people could cross.

Casey stopped in the middle of one of the sections, trying to puzzle it out. He stared up at the red lights suspended over the street, since many of the drivers were watching it. While he was watching the light turned green and Casey heard the cars rev behind him. Yelping, Casey threw himself toward the closest sidewalk, barely getting clear before a car could hit him.

Casey tugged on his shirt and glared in the direction the car had gone. Hadn't they seen him?

Casey kept going, scanning the crowd and making sure to only cross the street when other people were. He was confident he'd find where he needed to go soon.

But as the minutes passed and Casey continued to find no clues, he began to worry. He was losing valuable time he couldn't afford.

Casey ducked into an alley and took out the picture again. He ran a finger over the image of his younger Sensei.

"What am I looking for?" Casey whispered to the picture. "Where am I supposed to go, Sensei?"

Casey's finger slid down the picture. He hesitated, then pulled the picture close to his face, squinting at the book held in Commander O'Neil's arms.
"'Eastliard University'?"

The left corner of Casey's lenses flashed, indicating a known location. The mask had been made by Uncle Donnie, so of course it would have a map of the city where he'd grown up! Which could also mean…
"Take me to the lair," Casey tried.

Nothing.
"H-home?" Casey choked on the word for some reason. "Take me home?"

The lens flashed, then a highlighted path appeared in front of him. Casey silently pumped his fist and took off again, following the path at a run.

Distracted in keeping his eyes on the path, Casey didn't notice at first when everyone was suddenly gone from around him. Looking up, Casey found a pair of headlights headed right for him!

"Woah!"

Casey threw himself backward, tucking and rolling so he came back up on his feet.

He huffed at the person next to him, "Doesn't anyone watch where they're driving around here?"

The man didn't react, as the people started crossing the street just then. He could have at least said something, though. Casey moved along with the flow of people, wondering if people in the past just didn't pay attention to what was going on around them. To Casey, that seemed like a fast way to get hurt or killed.

As if he hadn't almost been hit by a car twice in ten minutes. Casey let the thought go and focused on following the path while also avoiding getting run over or run into.

"You have reached your destination."

Casey startled at the monotone voice in his ear. He looked up from the sidewalk, his eager smile quickly turning to confusion.

It was a regular building, with big glass windows and doors and a sign that said, "Qwik-Mart". The entrance to the building was obvious, but there weren't any handles on the door. Casey squinted inside the darkened building through the glass, wondering where the entrance to the lair would be. And how he was supposed to get inside. He walked back-and-forth in front of the building, looking for an outside entrance, but still found nothing.

"Maybe the GPS is busted," Casey muttered.

The mask had sometimes malfunctioned ever since his mom had fallen off that building, cracking the mask and her skull. And the maps were over twenty years old, so maybe it was incorrect.

Casey threw up his hands with a groan. He was right back where he started: lost! As he turned away, though, he noticed a sign with a familiar name.

"Eastliard University, one mile?" Casey read, his grin returning. "Talk about-"

Casey clamped his mouth shut. He made himself calm down; getting loud and excited rarely ended well. Once the jittery excitement passed, Casey turned and trotted in the direction indicated by the sign.

As he went, Casey realized he didn't know what he was going to tell Commander O'Neil. If he jumped out and said he was from the future, would she believe him? She knew his uncles, so maybe if he opened with saying something along those lines? At the very least, it would get her attention. Then he could explain the whole time travel deal and how he'd been sent back to save the world from being invaded.

"Easy," Casey thought with a grin. "Don't worry, Sensei… I'll fix everything."

Casey soon reached a massive building with a stone courtyard in front of it. He gazed at the dozens of darkened windows and lack of people. He wondered with a start of alarm that he didn't know if Commander O'Neil would even be at the university! Did she live there? Or just visit?

Casey grabbed his mask, telling himself for what felt like the hundredth time to focus. There was too much riding on him for him to let his mind go in a dozen directions. He just needed to find Commander O'Neil first.

He needed to do some recon. There were only a few lit windows, and Casey knew that he'd be able to see into them while remaining fairly hidden if he got onto the roof.

Get to the roof. A manageable first step.

Casey swung to the roof with his grapnel. He started toward the furthest corner to begin his search, but clattering below made him drop to the roof. He peered cautiously over the edge of the roof as someone hopped out of a window and into the courtyard.

He squinted at the figure. Maybe it was just wishful thinking, but he only knew one person with hair like that. Casey zoomed in with his mask with the figure, right as she fumbled with her phone, barely missing catching it before it hit the ground.

Casey grinned. Yep, that was the commander.

Casey hesitated for half a second before hopping to his feet. He hooked his grapnel to the edge of the roof to swing down and drop right behind Commander O'Neil with a happy cry.
"Commander O'Neil!"

Which, in retrospect, could have ended very badly, given Commander O'Neil's almost inhuman reflexes. Could have, except she didn't seem to have heard him. Commander O'Neil slung her backpack onto her back and trotted out of the courtyard, a proud bounce to her step.

Confused, Casey didn't follow at first. He tried again, "Commander? Er, April?"

Commander O'Neil didn't pause.

"W-wait, hey!" Casey yelped, running after her. "Don't ignore me, I just have to- Commander!"

Commander O'Neil didn't seem to notice Casey running alongside her. He knew she had to have heard and seen him, but she didn't even bat an eye.

"Commander?"

Commander O'Neil was determined to ignore him, but Casey couldn't give up or even take his time. He ran in front of her and blocked her path with his body.

"Commander, I have something to tell-"

Commander O'Neil didn't stop, didn't hesitate. She just kept walking, right into Casey-

A chill ran through Casey from head to toe. His vision blurred, went black, then jolted back to normal. He stumbled back, shaking from… whatever had just happened. He turned, keeping his feet under him with effort.

And still Commander O'Neil walked on, unaware that she'd just walked through Casey.

A/N: ...welp.