It's over faster than it feels like it should be, and Derek let's the second alpha slide limply to the floor, his chest a complete ruin where Derek had simply reached in and up and ripped his heart free. After that it's only a moment's work to turn to the other, the man's twin, apparently, crouch down and take his throat out with an almost casual swipe of claws.

Except there's nothing casual about watching his red eyes go human and then dark. Nothing casual about killing a paralyzed opponent. He can't find it in himself to regret it, though, not with the stink of Stiles' blood and fear thick in his nostrils, of Erica and Boyd's layered so deep into the concrete of this place it might never wash clean.

He stands for just a moment, looking down at his handiwork, then turns back to Stiles almost on autopilot, bending to set him and his chair upright and facing away from the carnage, then slash his bonds with uncharacteristic gentleness before he turns away. Stiles shouldn't see this. "Don't look," he rasps, his voice sounding rough and unused. Broken. He can hear someone else upstairs now, quiet and careful. Scott, he expects. Or maybe Allison. She's brave enough. He can't scent whoever it is over the overpowering stench of blood and death. "I'll find some towels. Or something. Just... don't look."