'If you leave marks on me, you'll be in serious trouble.'

He's teasing, except for the way he's really not. But it doesn't sound like he minds the sensation for now, and he starts a hard rhythm because he likes that noise out her, and the way she's coming to meet him, working for her own pleasure. He rolls her nipple between his fingertips, pinching a little, twisting gently in counterpoint to the firm thrusts between her legs.