A/N Takes place just after the murder of the Potters, but before the torture of the Longbottoms.
Too Late
"You knew," I accuse. "You knew they were going to kill her."
The Disarmed woman on the ground in front of me just grins, her teeth glinting in the moonlight, like perhaps she and Fenrir shared more than just the Mark on their forearms.
A wand flashes red. My wand flashed red. But it had mutated into something alien; far from being an extension of myself, it had taken on a life of its own. I vaguely hear a scream.
"Why?" I yell.
She spits out a mouthful of blood, but still manages a look of such condescension that her relation to her cousin was accentuated. I had seen that look on his face before, by the lake.
A wand flashes again, and the figure before me writhes in obvious agony.
After what could have been seconds, or hours, the torrent of magic stops abruptly, and I slump to her level. I hear panting. She lies on her back, gasping for air, horribly stripped of her pride, but still manages a glare that conveys her undying hatred. This is not a forgivable offense.
But I don't deserve to be forgiven.
Slowly, I stand again.
"Get up," I command harshly, in a voice that is not my own.
She wordlessly stumbles to her feet, and though she must know what I am about to do, she just smirks, arrogantly shaking back her matted hair.
I see a flash of green through a window, a body fall, and I know. Merlin, forgive me. Lily.
Closing my eyes, I take a deep breath, hungrily consuming the fresh air to fill my constricted lungs. "Avada Kadavra!"
"I'm sorry!"
"Save your breath."
"I never meant to call you Mudblood, it just—"
"Slipped out?" Lily's face was cold and impassive. "It's too late."
A shrill laugh brings me back to reality. "You have to mean them, Snape."
The threads that are holding my composure together snap; I have finally become what she's been goading me toward for years. I have become her.
"CRUCIO!" I scream, saying the spell out loud for the first time.
With a last disgusted look at the writhing figure prostrated once more on the ground before me, I turn and walk away.
The first tinges of insanity echo in her laughter behind me.