It's almost certainly blasphemy for him to feel this good. Like they match, like they were meant for it, and all the other terrible, purple prose that Jacob never understood. Astarion squirms and Jacob gives his ass a playful pinch, but he rocks hard into him. There's half a breath of time between one move and the next, but he pushes himself deeper, back arched over him so he can kiss him as they move together.