She comes to Remus through the darkened hallways of her cousin’s house, skin as pale and hair as dark as she can make them. He’s sitting on the dusty bed in the room Sirius had given him, sloppy drunk, and the books open on the bed around him stink of dark magics, magics powered by blood, and revenge, and sacrifice. His lips are bitter with the moonshine as she pushes him away from them, down into the dust, and she kisses him until she feels drunk with it herself.
Snape corners him in the teacher’s lounge. “You can’t do this,” he spits, furious, backing Remus up against the way. “You never used to be this cruel--She’s not Sirius and you know it.” Remus pulls away from him, growling—“Who the hell are you to judge me? You think I don’t know? Do you really think I don’t know how it was after Lily died?” Snape flinched physically at that name, and suddenly Snape’s hands were tight around his neck. Remus could have cried with gratitude, thought ‘Do it—do it.” But the traitor let go, and disappeared out into the halls.
Her hair is mouse-gray the next time Snape sees her. Even through the hood, he can tell. The light behind her eyes has just… gone out. She doesn’t need red hair to look like lily then, disappointed, angry with herself, disgusted. One of her companions sends a spell arching blue-green down the wrong corridor, and he has a perfect line of fire to where she stands. He turns away anyway, hates himself just that little bit more. He’s no better than the damned wolf.