I'm in Survival Hell, You're in Party Heaven
Or rather, she wanted to turn herself into me, to escape the fact that she had killed me.
Dad stood in the doorway, holding a freshly cut key in one hand. He slid it into the lock, turned it, and sealed the heavy iron door from the inside.
Then he walked over to the ventilation shaft and dropped the key in. It clattered down through the metal pipe, the sound echoing and fading, growing smaller and smaller until it was gone.
"This is a full containment test," he said into the dark.
His voice was calm in a way that was almost worse than shouting. "There can't be a way out. That's the only way to force out what's really there."