Shipping wars
From Super-wiki
Shipping wars result when tensions arise between fans of two (or more) different character relationships (or 'ships) in either canon or fan fic. The fiercest wars occur between adherents to different OTPs.
In Supernatural, there is a noted absence of shipping wars, due to the presence of only two main characters - Sam/Dean - if a fan is comfortable with Wincest. In Season One, for fans of het, there was some tension between fans who saw Sam/Jess as the OTP, once Sam/Sarah emerged after Provenance, but this was relatively minor.
In RPS, more opportunities for tension arise. Jsquared is the OTP for most, although both actors occur in a number of pairings both slash and het.