"I like to start at the top," she says. She is almost whispering. His eyes are intent on her face, but his fingertip comes to rest at the skull’s head. Waiting for instructions. "I like the way it is rounded – how I can feel the ridge of it through the skin." He traces it, fingers gliding up and down over the curve and back again, ever so slowly. It feels like someone is running smooth metal over her arm. "Then I like to trace the eyes – one after the other."