Derek is stunned by the tone of her voice even before she punches him. The surprise of it is enough to have him rocking slightly to the side and he looks over at her with furrowed brows, expression the portrait of confusion as he reaches up to curl his hand around his shoulder.

"Ow," he says even though it didn't really hurt. He's so surprised and confused that he barely flinches at the mention of Stiles, though he does feel the need to defend him. "No, he-- Stiles didn't do anything."

Derek swallows hard and blinks a few times, head tilted curiously. He tries to see himself through Kate's eyes, but he just can't. All he is is this broken thing, made up of pieces too jagged to hold. He isn't good for anyone. How could he be? "I'm just-- I'm messed up."

It feels like a dumb thing to say, but true enough, and he doesn't know how else to explain it.