Derek freezes under Stiles' gaze, jaw tight and expression flatly blank as he resists the urge to hide his blood-soaked hands behind his back. He can hear more than one person upstairs now, movements cautious, obviously expecting attack. The sound of Stiles voice, though even whisper soft, drowns out anything else, and Derek frowns.

"Don't. Don't be sorry," he rasps, and he starts to move closer before stopping, looking down at the blood drenching him. "You saved them. Don't ever... don't be sorry for that." He takes a half step back and tips his head towards the stairs. "Down here," he calls, voice tight and painfully controlled. "Stiles is... he's safe." Fine would obviously be overstating it. "Bring... bring towels and sheets or something."