Stranger Than Fiction (http://nyxocity.livejournal.com/187348.html)
Summary: Set immediately post-The Monster at the End of This Book. Dean can't stop wondering why people would write gay porn about him and Sam. Research takes him to interesting places; re-reading novels for subtext, visiting message boards, and a really freaky place called LiveJournal. What he discovers is a sick fascination with fanfiction, more about gay sex than he ever wanted to know, and an even deeper obsession with understanding why people write this stuff. Meanwhile, they're hunting a mysterious monster that takes the form of a person's truest love to kill them slowly, the lines between fanfiction and reality are starting to break down, and they still have to stop Lilith and save the world.