Psi frowns, rolling his eyes (not that anyone can tell).

"You say that like it will make sense to anyone but you." He throws his arm out as though to emphasize the amount of details Foster has yet to address. "How are you a disease? What do you do that is disease like?"

Just some sample questions pointing out the irritating vagueness of Foster's responses. He's grateful Foster is responding at all, but he wished the human could be a little more demonstrative in his explanations.