This is interesting to me because last night I had a dream where I was driving around an old childhood friend of mine, who appears semi-often in my dreams although we haven't spoken in years. I vaguely remember asking him bluntly "why do you keep appearing in my dreams?" and after that he just vanished from where he was sitting.

Granted I've apparently been able to lucid dream for some time now, but haven't had a conscious interest in it again until very recently, so chances are by me 'questioning' this character I just completely destabilized the dream I was in. It's good to know there are others interested in this question, and I'd like to pursue it more once I am more skilled at controlling the dreams.