From Fan History Wiki
There are several examples of kerfluffles in the Harry Potter fandom. One such kerfluffle involved writing what people called pedofic, stories featuring minors involved in sex acts. Another kerfluffle was the Great Ship War in 2000 which led to the eventual creation of Sugar Quill.
There have been multiple kerfluffles over hate memes and their role in the fannish community. A lot of people hate them for their anonimity. Some people think they are a healthy way to vent feelings.
Real Person Fic
Fandom has repeatedly fought over this topic for years and years. Is it right? Is it ethical? Is it legal? Both sides are rather entrenched in their views.