A/N: This is the beginning of a TMNT/"Stranger Things" AU I started over on tumblr. Definitely will contain spoilers for the show if you haven't seen it yet - and I highly recommend you watch, it's on Netflix. :)

I shuffled some characters around a bit, but it should be easy enough to follow if you're familiar with the source material.

Don's voice breaks mid-word, and he drops his face into his hands, curling into something half his height and trembling and terrified.

"Leo, I think I– I think I'm going crazy."

It would be easy to think as much by looking at him, sitting on the floor with a naked lamp in his lap, surrounded by seven more, several strings of Christmas lights a tangled mess at his feet.

But Raph's green eyes are sharp and fierce, and he wraps an arm around Don's shoulders that probably feels like steel.

"You are not," he bites out. "Somethin' took the kid, somethin' bad. April saw it, too, remember? It took her friend Irma, right out of Casey's backyard. You got a picture of it, Don. We believe you, man."

"Even without all the proof, we believe you," Leo said, meaning it with every inch of his heart. "Something took him, but we're going to get him back. We're going to find him, I promise."

Don did get a picture, prowling the woods around his house, alone, at night, armed with nothing but his precious camera. And the picture was terrifying, certainly. A picture he showed them with shaking hands the day he developed the film, of a twisted figure standing behind Irma Langstein the last night she was seen, pale and faceless and distinctly inhuman, like a monster out of their D&D game.

But it's infinitely more frightening how close Don put himself to danger, how little he cares about himself anymore. He doesn't eat or sleep or go to class, he just sits in this empty house surrounded by lights that aren't even plugged in, while his adopted father (a grizzled old veteran nicknamed Leatherhead) and Leo's father (Chief of Hawkin's Police Department) tear the town apart.

They found the bike abandoned just off Mirkwood Road, and a half-loaded shotgun in the back shed. There was a hole in the wall from where the front door slammed open, and a few pictures frames were knocked askew along the hallway, all signs of running and danger and fear.

And Don blames himself, hates himself, for not being home.

"But you can't do this to yourself," Leo says firmly. "All this stress isn't good for you, you know better. He's a resourceful kid, and he's smart, and wherever he is, he's fine, and we're going to get him back. No matter how far we have to – "

"That's just it, Leo. I don't think he's far at all. I think he's – "

The radio across the room comes on with a loud click, dial wagging madly through white noise and weak signals. The three of them freeze, going utterly still and silent, like a trio of frightened rabbits; and Leo forgets how to breathe, and Raph uses the arm around Don's shoulders to curl fingers into the collar of Leo's shirt – but Don inhales softly, hopeful and anticipating, like he's been waiting for this all along.

The lamp in his arms lights up, a white so bright it burns – and how, it isn't plugged in, the cord is laying right there. Leo shields his eyes against the strength of it, momentarily blinded, but he can feel Don lean forward, lean closer.

And then, impossibly, a familiar voice on the radio says, "Donnie?"

And Don laughs in stark relief, but it comes out like a sob, and once he's crying he can't stop, and he scrambles blindly forward on his hands and knees.

"Mikey! Oh, god, Mikey, I'm here!"