<p>I’m sure that’s rare and I’m skeptical it even happened (but hey I guess they can’t control the interviewer). In my interview (and in all of my interviews for schools like Princeton), we talked about the things I was interested in. Why I wanted to go there, what I hoped to get out of it… basic simple things. The only “preparing” I can recommend is to think about a couple of specific things to say in response to those types of questions. Maybe have an anecdote. But really, don’t over-think it, get stressed, or try to oversell yourself. Just have an honest conversation with the person and you should be fine.</p>