The face had been designed for infiltration, and was flexible enough to mimic human movements. Thus, she could part her lips slightly and lean in to return the kiss as she'd seen people do in Jeff's collection of explicit materials.
After a few moments she pulled back. "Do not worry," she said. "I have noted this weakness in you, but will not exploit it. I have merely filed it away for when I must eventually destroy all beneath my feet." She tipped her head. "That was a joke."