I dreamed up fanfiction ideas years before I knew what fanfic even was. I didn't write them (which is probably a mercy), but I was definitely thinking beyond the boundaries of any given narrative, as if it were simply a small snapshot of a world as large as the real one. That impulse -- to ask something as simple as "what happens next?" or as complicated as "if this plot device does that, then what if someone did something similar over there two hundred years ago, with such-and-such results, and then someone from over there sent a message to the main characters..." -- is as natural as breathing.

I do sometimes read RPF written by authors I like for their other work, but always with a kind of squiggling feeling in my gut. It fascinates and discomforts me in the same way as watching a car crash or a house fire. I really have no idea how people perform the mental trick of seeing real people as characters while also paying enough attention to their real lives to build the equivalent of an agreed-upon canon knowledge base.

I would do a survey, but obviously any response based on my f-list would be massively fandom-biased. *wry*