Foster has also met Jasper. He found her one of the more tolerable personalities he collided with during the ball.

"But it does." His eyes narrow slightly, and his smile drops, just for a moment. "My purpose benefits you."

Then he gets back out of the man's space by straightening up, his smile returning in a friendly way.

"Whether or not you serve a master now, you will."

He's actually going on his sixth day without eating, but his purpose is sustenance of a kind greater than flesh--

Which is to say, he's running on sheer force of will and an unhealthily strong sense of disconnect between his brain and his body.