If I already know the person and we interests in common (i.e.: movies, tv shows), then I'd ask them "have you seen this movie/tv show?" or ask them if they have any good recommendation, etc. Trivial stuff, nothing too deep. It keeps the conversation flowing.
If I don't know them, I may ask them (depending on the situation) where do they live and make small talk about their city (If I haven't been there, then I'll ask them more about the general location, or even where's located). They may suggest some places of interest or restaurants, etc. - this may take you to the next topic, and so on.
Suppose you were a twin, you both were given in adoption, would you be looking for your twin?