Sometimes I have watched videos where the description says that it is two straight guys experimenting for money, or one gay guy having sex with a straight guy and teaching him how to be gay. I enjoy these videos sometimes. It is exciting i guess, to see a man do gay things for the first time. I am not sure why this makes me excited. It just makes them look vulnerable or something. But your guess is as good as mine... I know you are talking about fanfic so I will add that I have read my share of slashes, anime stuff. I find it exciting too.