Here's an idea which I think I'll never get round to writing properly. Man writes stories for SOL. He tries a really hard porn type story and gets enthusiastic mail from a reader. The carry on the conversation, with the emailer becoming more forthcoming about the BDSM porn he has actually had...but also with little bits of home details. The writer slowly realises that the emailer is his father. What to do then when this person has told him about stuff (like with his sister, his wife's sister, etc, etc). Could be humorous or dark. I just don't know.