Hissing loudly, he could feel her nails just scraping skin off his back, which meant that his nano technology might start repairing it soon. But his brain was in a pleasure mode, and that might stave off any sort of repairs if it associated the roughness with feeling good. He dug his feet in harder and moved harder, his hands moving down to hold her hips in place as he thrust into her as hard as he could manage. Perspiration had started to form on his forehead coupled with a mixture of moans and grunts coming from him. He didn't want to hurt her, but he knew with his newfound strength he could probably make her into an imprint in her mattress.