I'm a pretty unremarkable guy. 30-odd, white, male, professional, educated but not a prolific reader of fiction.
I wrote a few stories on the Lusty Library 5-10 years ago - now lost I think - and went five or six years without writing anything. I initially started to write again as an outlet to prevent myself cheating on my wife, to some degree or another. It lets me confront my urges without hating myself, and hopefully construct something positive and worthwhile out of them. Although I don't like most of the writing process, I generally come to like the end product (I wouldn't post otherwise) so that's good too.
My stories are my fantasies committed to writing. My 'girls' are always based on people I know with only the name changed and a little dramatic license, but my 'guy' is rarely a straight portrait of me, though I think I'm always in there.