Derek smiled against Stiles' skin. Sometime--later--he would want to try this again, and test all their stamina. But right now, fast was fine. "Are you ready Stiles? Ready to come all over Isaac's ass?" He moved his hand, wedging it between his slaves' bodies to wrap around the base of his cock, where the metal cock ring kept the boy erect, and nudged the boy's ballsac with his thumb.