He waits, then waits a little longer, looking at her, taking it in. Then he swings the crop through the air and catches her on the side of her left breast, then her right, then her left again, not as viciously hard as he could but hard enough to leave flushed pink marks. And he keeps going, moving in an easy, smooth rhythm, pausing at last to admire his work before the crop whistles through the air again, harder than before, hitting first one nipple directly and then the other.

There's a focus in it, a concentration. It's almost soothing. But when he sees the evidence of it on her skin, his pulse races a little faster.