You Can't Leave! tmnt fanfic

This can't be happening!

Donnie's pov

I finally finish my latest batch of retro mutagen and start carrying it to its holder. When Mikey comes up behind me and scares me. I let out a yelp and the canister goes crashing to the ground, the retro mutagon splatters all over the floor of the lab and I turn around to yell at Mikey, when I see the stuff swiftly making its way to his heel, I remember how even a drop of it can cause a mutant to unmutate and go back to how they originally were.

"Mikey! Step away!" I say and the ooze gets closer to his foot. He looks down behind himself and yells.

I jump, start a front flip sand grab his shoulders, I complete the flip and he goes flying to a wall and I step in the retro mutagen from the force of the throw,

"GO NOW DON'T WA- AAAAAHHHH!" I start to yell from the pain and Mikey tries stepping closer but Leo comes in and holds him back. The pain becomes greater and I scream louder then, I stop. I shrink and eventually I am to th---------

Leo's pov

"DONNIE!" I shout as I see the normal turtle on the floor. I come up to him to try to see if he is trying to communicate with us somehow. I can hardly hear anything over the music Donnie had playing on the stereo of the shellraiser so I turn to Mikey, "TURN THE BLASTED MUSIC OFF!" I yell and he rushes to do so.

I wait for a second to see if he will do anything and, nothing.

"WHAT HAPPENED!?" I yell at Mikey once again and Raph walks in obviously oblivious to what just happened.

"What he do this ti- Hey where's Donnie?" He asks and I pick up Donnie and show Raph.

"I'm confused why is Spi- that's not Spike." He says and I nod no, unable to speak.
"No. NO! THIS DIDN'T HAPPEN! THIS IS JUST A SICK JOKE, THAT IS JUST A TURTLE. THAT ISN'T DONNIE. It.. it isn't. him." He says giving up and walking over to me. I hand him Donnie and brake down crying. He is a normal turtle now and I have no clue how to fix this. Raph puts Donnie on his shoulder -like he sometimes does with Spike- and I notice the retro mutagen on the floor has made a huge puddle.

"Guys, we n-need to do so-mething about th-e retro mutagen." I stutter from the crying.

"How?" Raph asks looking to Donnie and then to the ooze on the floor. I look around and see a bunch of syringes on a table.

"Take a syringe and use them t-o collect the stu-ff." I command still stuttering a little.

They all nod and do so, it works well and we collect it all. I look to Raph who has red eyes and a wet mask. I go over to him and wrap him in a hug. He doesn't hug back for a second but the sorrow and confusion takes action and he hugs back. Mikey joins and we stay like that until Donnie falls off Raph's shoulder and crawls to his table.

"What's he doing?" Mikey asks,

"I don't know. He might be trying to communicate." I say and we walk to him. I pick him up and put him on his desk. He walks to the regular mutagen and looks to us. I take the canister and look from it to him.

"What does he want us to do with it?" Raph asks with hurt in his voice.

"He wants us to add human DNA to the mutagen and drop it on the floor he will then be exposed to the mutagen and hopefully go back to being Donnie. There is a 48.765% chance of it working. There is also the same chance if we do it without adding DNA to it but there is also a chance of him ending up like Spike or not remembering anything." Mikey says, Raph and I look at him in shock and awe.

"How the shell do you know this!?" Raph asks in utter shock.

"Maybe I'm smarter then you guys were always led to believe." he says looking down and rubbing his arm.

"Or maybe I spend way too much time with Donnie." he says looking up with a sad smile. "He was worried something like this would happen so he made me memorize all that fun stuff the day he created the retro mutagen. I memorized everything, I've even tried making it a few times, it's always worked. I can totally do this!" he says cockily. I relax a little but Donnie is still a normal turtle. It's scary!

"Well I guess that's good but, have you ever actually tried it!? I mean this is actually happening! So don't get to cocky! Just tell us what to do so we can get our brother back!" I yell I immediately regret it though because his happy proud face turns sad. "Oh my- I am so sorry I'm just stressed out, sorry bro. I believe you can do this just tell us what we need to do." I apologize.

"It's fine bro. I get ya. We can't let Donnie stay like this for long though. Get Casey down here. I can get his DNA and add it to the mutagen." Mikey says. Raph pulls out his T-Phone and Mikey and I pull away.

"Hey man, you need to get down here.......... You'll find out just get down here................. I'm NOT Leo. Just get down here will you!............ Thank you geesh.........yeah." he Raph says and hags up. "He's coming."

Casey's pov

I walk through the door of my room to get my phone, I pick it up and it immediately starts ringing. I look at the contact and answer

"Hey Raph what's up?"

"Hey man, you need to get down here"

"Ok dude, but what for? You sound, upset.

"You'll find out just get down here"

"Ok,Ok I'm coming, geese. When'd you become Leo?"

"I'm NOT Leo. Just get down here will you!"

"Ok, I'm coming gosh."

"Thank you geesh."

"I'll see ya there in a few minutes. Ok? bye"

"yeah"

What was that about. Oh well I better get going.

I make it there in three minutes with my usual battle ready attire and face paint

"I'm here guys! What's up!?" I yell to the empty room.

Raph walks out of Donnie's lab with a turtle on his shoulder, I can tell it's not Spike.

"Get a new friend for spike? And also why do we still call him Spike? We know he likes Slash better."

(They got Slash retro mutagen after the Mutanimals split up. No one really knows why.)

"Donnie said that if we do some sciency junk might happen so yeah what ever. And no this is NOT a new pet. This is Donnie." he says handing me the turtle.

"Ha ha very funny Raph I tooootally believe that this is Donnie. If you really want me to believe that then your gonna have to-" I start but Raph interrupts me.

"It IS Donnie. You know me better then to pull a joke like that! It is Donnie. We have a way to bring him back but we need you for it. I know you aren't the biggest fan of him but please. We need our brother." he says and I realize, this is happening.

"How can I help?"