So the first time Stiles got Derek on his back, worked him open and pressed inside with the long exhale of a perfect fit, he wasn't expecting the sound. Sure when they exchange handjobs, or blowjobs, or any other kind of orgasm, Derek can get a little vocal – sometimes even demanding in a hesitant sort of way – but the deep moans, the sharp grunts, the cursing and the constant use of Stiles' name was not expected.