There was an infamous bit of Ship-to-Ship Combat in X Japan fandom that actually led to legal threats being made and a large swath of bandslash being deleted out of fear of the Big Name Fan making them. It started around 2008, when a rabid Yoshiki x Toshi shipper managed to acquire status with a then-official forum. The shipper happened to loathe hide and anyone who shipped hide x Yoshiki, and went about issuing legal threats to (and having her friend who was The Cracker hack) several well-known hide x Yoshiki writers. Most writers of the pairing deleted their fics or apologized or went underground at the time - the result being the deletion of almost all extant Yoshiki x hide or hide x Yoshiki slash at the time, unless the writers were so stupid as not to care about the possibility of legal action, or so angry they ignored it. Eventually the Flame War and the threats calmed down due to a variety of factors (the BNF losing official status, Yoshiki being far more open about his love for hide to the point where it became as close to canon as Real Life gets, hide fans and Toshi fans no longer being in open combat due to the events of 2010) but the result remained - anyone looking for slash in the fandom with that pairing likely will not find anything of quality.
Not even the Vocaloids could avoid this one, despite the fact that the canon changes with EACH. FREAKING. SONG. Because there is no official canon source to determine who should be paired with who, you'd think the fans would just mind their own business, right? Nope.
The most obvious arguments being KaitoxMeiko vs. KaitoxMiku and RinxLen vs. either one with anyone else.