The kiss caught Derek by surprise, and his lips parted. He was stiff for a moment before relaxing into it, and he put his hand on the boy's hip. It was a disciplinary offense, and a well-trained slave would never presume. But he got the feeling that Stiles was more tactile than the werewolf had suspected, and perhaps needed touch--even if it was just casual touch--as much as any wolf.
He could taste himself on the boy's tongue, and though not something he usually enjoyed, he made a small sound of pleasure at the discovery before pulling back, turning his face to the side to press a soft kiss on the boy's jaw, his temple.