Derek moved again, pressed against Stiles' back as he knelt between Isaac's legs, his erection bumping the boy's back as he hooked his chin over his shoulder to look down at the younger werewolf, presenting himself so eagerly. He nuzzled the side of Stiles' neck as he spoke, affectionate. "He wears a plug for me," he murmured, his hands roaming over Stiles' skin, possessively. "Keeps himself prepped and ready for me. Only takes it out to sleep. But maybe next time, I'll fuck him open for you, and fill him up with come."