"How?" Derek continued to slowly fuck Stiles' ass with his fingers, the needy sounds going straight to his cock. He'd so far kept his body separate, except for his fingers, but now he leaned over the teenager's prone body, his thighs pressing against the backs of Stiles legs, rough denim against smooth skin. He nosed against the back of Stiles' neck and ear. "And what did you do to deserve it?"