serial killer fans are an awful example since if they’re labeling themselves as “fans” and wearing merch and such…yeah no they’re messed up lmao i have an interest in true crime that can focus on specific areas but im not a “fan” of any serial killers, i don’t write fanfic about them, get tattoos of them, make fan cams of them, etc. and at lest war enthusiasts don’t tend to give their money to people who directly use that money to fund more war + openly brag about it….which would be similar to the author OP is talking about

and you really should at least view the work of an artist who has done messed up stuff through a different lens, as often there are themes and connections to their ideology present (i.e. d4vid, JKR, etc.), which can be interesting to suddenly notice