Inspired by a gif set on Tumblr.

Also, you can totally blame John Green and Crashcourse for my headcanon Peter being a history teacher.

New title comes from the quote "You look like a winter's night. I could sleep inside the cold of you." Koschei from Deathless

Series title is the Ancient Greek word for a substitute or changeling.

XXX

It's his free period and he's trying to figure out how to get his students to understand that the French revolution was even more important than the American one. Focusing on his lessons helps him ignore the memories. Though it's a close game.

The familiar squeaky door hinge is his only warning. He looks up and there's his own personal nightmare, Lydia Hale.

She looks obscenely good in her dark blue dress and heels. The smile she gives him, though, has too many teeth. "Hello Peter."

"Go away," he returns his focus to his class prep.

He doesn't even hear the click of her heels as she moves, and before he knows it she's sitting on his desk, legs crossed and skirt hiking up even further. He hates that his madness has taken the form of the nineteen year-old girl that nearly killed him. The scars on his cheek and neck twitch.

"Now, now Peter. Don't be so rude." Too sharp nails grasp his chin and force him to look her in the eye. Her hazel eyes flicker red like embers in a fire. He shudders. "After all I'm here to help you."

He gives a bitter laugh. "Help me? Lydia the only way you could help me is by going away!"

She gives a moue of distaste. "Unfortunately Peter I can't do that, not yet."

For a moment she looks far too human, and he has to keep reminding himself that she's a monster; the prettiest monster there ever was. "Are you even real?"

Anything to know that he isn't going crazy. He needs that stability. The smile she gives him this time is full of secrets. "Strangely enough," she leans down and he can feel her breath ghost over his mouth. "That too can be answered with, 'not yet'."

She kisses him, and he tries to struggle away, but she's far too strong. Stronger than she has any right to be. Her claws dig into his scars making them deeper, and the blood streams down his neck.

"PETER!"

The shout gives him a start and he finds himself staring at Mrs. Morrell who looks concerned. "Peter are you alright? I heard you screaming."

He can barely hear the whispering of the students in the hallway. He gives her a tight smile. "I'm fine Angeline."

It's clear she doesn't believe him but she lets it go. "Don't forget our next session is tomorrow."

He nods. "I'll see you then." The idea of more lies makes him ache, but there is nothing wrong with him.

And sitting in the back of the class Lydia Hale smiles. She never loses, her inevitable victory is only. . .delayed.