The five times Derek called the Sheriff "Dad" on accident and the first time he did it on purpose.

And with his fingers pressing inside of him and his cock brushing against the sheets and his face in the leather that smelled like Derek, he felt pathetic and desperate all at once. He knew that if he ever got the chance (the opportunity) to be with Derek that he’d ask him to fuck him within half a second. He wanted the older man inside of him and around him and all over him until his senses were so consumed that he was completely senseless. or The five times Stiles fingered himself and the one time Derek did it for him.