I got this idea a few weeks ago after watching an episode of Criminal Minds. I think it was season 7 or so, and the episode was called 'foundation'.

This takes place after the season 1 finale, somewhere before 'The Wrath of Tiger Claw'

April sighed, supporting her head on top of her hand, blankly staring outside of the window. Rain was hitting the window with such force she was sure it would break any time soon. Occasionally the sky would light up, and a loud thunder would echo through the air.

The red-haired teen sighed again and looked towards her mobile, still turned on and focused on her messages. Casey still wasn't answering, she had sent the message 30 minutes ago, and still no reply came from the teen.

"Fine" She huffed, standing up angrily and picking up her jacket, folding it around her body to keep herself warm. She turned off her phone and placed it in her pocket, walking outside the room and through the halls of the lab.

She loved her job, even though it was obligated from the school to take a job, she still loved it. She always loved animals, so working with them was something she really liked. But at times like these, she hated it.

She hated having to walk through the rain, and just when she needed him, she couldn't reach Casey. He had promised her she could call him whenever she needed a ride, and when she actually needed one, she couldn't reach him.

She knew she was being ridiculous, Casey didn't need to pick her up or something, but he still promised her he would pick her up, and right now he wasn't even answering. And that was something that pissed her off the most.

She turned off the light in the halls as she passed by, checking if every door on the side was closed and locked. Rain was still hitting the wall and windows, and she couldn't contain the shiver that went down her spine.

She never liked being the last one to leave the building. She didn't bother locking the place down but it was always so creepy, and that wasn't because of all the caged animals around her.

Many people thought it was a lab, and practically it was, but where she worked it wasn't. It was merely a research center, where they trained various animals. They compared the behavior of normal pets and normally 'wild' animals.

Testing how much could be learned to those animals. And of course there was a lab, where animals where tested but luckily she didn't have to work there. And her boss had assured her they weren't hurting the animals with the chemicals or anything. Not that she believed him on that part.

April folded her jacket around her a little bit tighter as she was almost done, and only 2 doors remained. A shudder went down her spine and she viciously turned around. But there was nothing, only the darkness, and the only light coming from the windows.

The red-haired teen frowned slightly, she was sure she heard something but there was nothing. She let out a short breath and turned around again, ready to walk towards the door to lock it when something was placed on her shoulder.

She let out an icy scream which was cut off by a hand being placed on her mouth. Her eyes went wide and she reached for the attacker, elbowing him in his stomach. A painful grunt came from the boy and she turned around, facing him.

"Casey?!" She practically yelled as she saw the teen standing there, rubbing his stomach slightly. Her heart was still beating viciously and she was trembling slightly from the shock. Casey looked towards April, smirking slightly.

"Hey Red" He chuckled, flashing a grin. April huffed, crossing her arms over her chest and narrowing her eyes. She could feel her heart beating beneath her as she kept glaring at the vigilante in front of her, totally packed with his hockey sticks and even his mask.

"Don't scare me like that! " April called out, taking a deep breath to calm herself down and turning around again, ready to walk away when the same hand on her shoulder stopped her.

"Wait up Red!" He called out and turned her around against her will. "It wasn't that scary right? I just wanted to surprise ya" He said. April sighed and took Casey's hand and dropped it with a loud sigh. She had no right to be angry really.

"Let's just get out of here" April said after a while, turning around and walking towards the door at the end of the hall. It was the door that led to lab part of the facility. Somewhere she wasn't even allowed to go to.

"What's in there?" Casey asked, pointing towards the door where April was standing. The red-haired teen sighed slightly and pointed to the obvious sign that hung on the door, clearly 'Lab' written on it. Casey chuckled as he took a step towards the door.

"Wicked…." Casey mumbled and reached for the door, ready to open it already when April slapped his hand away. "What?! I wanna look?" Casey yelled, whining slightly and looking over to April.

"Forget it Jones, I'm not even allowed to go in there" She explained, slightly guilty from hitting Casey that hard. "Besides I just want to get out of here, this place is creeping me out at night" A smirk crept on Casey's face as he once again reached for the door, but this time opened it.

"No way red" He grinned, opening it further to peek inside. "Besides, I'm the one driving so I decide when we leave" He added with a smirk and fully walked inside, reaching for the light and turning it on. April sighed and walked into the room too.

"And I'm really starting to doubt if I should let you drive" April said, scanning the room too. Despite her fear of being caught, it was pretty amazing. "Where are the turtles anyways, I couldn't reach them either?" April whispered as she read the various signs on the doors.

"You don't know?" Casey frowned, raising a single eyebrow. April looked towards Casey and shook her head, indicating she didn't know. "They went to the park….." Casey said and immediately April's face fell as realization hit her.

"You mean, it has already been a whole year?" She whispered. A few tears appeared in her eyes as Casey slowly nodded. They didn't need words to know what Casey meant. It had already been a whole year since Mikey had died.

The last time they'd seen him, or found something that belonged to him was at the park in New York, so it was to be expected they would go to the park to honor his death, as much that could be honored. Her turtle friends had taken the death of Mikey hard, and they weren't the same ever since.

They were living their lives again, but the death of their baby brother was still fresh in their mind, and they never really overcame that loss. It took them a few weeks to even function normally again, and after that, life just went on.

Casey never got to know her youngest turtle friend. He died before Raph met him, just 2 weeks after the Kraang invasion. Casey came into their lives like a month after, and was one of the reasons why Raph was acting normal these days.

Of course, even after a month Raph was still mourning over the death of his baby brother, but it was less. And just as they thought he was going to be okay, his pet turtle Spike was mutated and betrayed him.

His brothers and him barely survived Spike's attack, but afterwards Raph was getting worse again. He always talked to Spike. And now he wasn't there anymore, and even betrayed him, and that hurt him a lot. And if it wasn't for Casey, he would probably still be sulking.

"Wait Casey!" April suddenly yelled, running towards Casey as he was trying to open a door. "I'm not allowed to go in there, my boss strictly forbid me" She said with a serious tone, Casey looked confused for a second but then chuckled.

"And do you even know what is in this room?" He asked, raising an eyebrow and smirking slightly.

"They said something about their most precious experiment" She informed him. "But he also told me that if I would ever look I'd lose my job. Let's just go" She said, tugging Casey's arm to get him to move, but Casey didn't move, instead he just grabbed the door handle again.

"Most precious experiment, and you never checked?" Casey smirked as he slowly opened the door. "Ladies first" He said, gesturing for April to go inside. April sighed, she knew there was no arguing with him, and to be honest, she was really curious after all.

The door wasn't locked, but it was only able to open it from the outside, so whatever animal was in the cage, couldn't escape. And you could only open it from the inside with a special key, which they obviously didn't have.

April slowly stepped into the room. It was completely dark so the only light came from the hall. She quickly glanced back and saw Casey blocking the door with his hockey stick, so it wouldn't close and enough light fell into the room.

There was a dark figure in the corner of the room, far away from the door. The chains were clearly visible and somehow April felt her stomach twisting. Nobody deserved to be locked away like that.

Slowly she took another step and froze. More light shined into the room, showing the green skin of the creature. Her breath hitched in her throat and she slowly shook her head. She recognized him immediately, the plastron, the shell.

The freckles that dotted his face. She took another step, looking closer towards the creature. Dirt was covering his green skin, scrapes and bruises decorating his skin. Chains around both his wrist and ankles, connected to the wall. And the worst of all, the muzzle on his face.

Another hesitant step was made and his body tensed, never looking up but April could see the clear trembling. She took another step and slowly the creature looked up. The baby blue eyes filled with so much fear April could feel her stomach turn again. She couldn't believe what she was seeing.

"…M-Mikey…?"