Wincest
From Fan History Wiki
Wincest is the umbrella name for the incestuous slash pairings that emerged in the Supernatural fandom. Although the sibling, brother/brother pairing of Dean/Sam is the most common pairing, it also encompasses the father/son pairing preference of some writers, that puts John Winchester in a sexual and or romantic paring with either of his sons, although the John/Dean pairing is more common than John/Sam. This pairing preference is sometimes referred to as Papa'cest or Daddy'cest. (Note: the latter genre-name convention is not necessarily limited to Supernatural.)
Given the fandom's love for Genderswap, there are also to be found a fair number of stories that posit either Sam Winchester or Dean Winchester as a girl, rendered so by either magic or curse, or in AU situations where one or both boys is and always has been a girl. The number of stories thus engineered with Het incest is small but not rare.
see also Dean/Sam
