Stiles swallows, watching Derek move down his body with an anticipatory nervousness. He doesn't want to move his hand back to Derek's head, because that seems too forward, considering, but he wants to, especially if that's Derek's reaction to it.
"That is...that is so okay, you don't even know," he manages to get out, his voice only going up a little. "Consider this total permission to mark me wherever you want, big guy."