We all have a friend who takes their fandom a little too seriously.
Maybe they own a collection of props actually handled by Daniel Radcliffe and Emma Watson, or perhaps they once uploaded a video of themselves to the internet drunkenly ranting about a casting choice with which they vehemently disagreed (to be fair, Jared Leto as the Joker wasn't great).
Those are signs that it's probably time to break into their bedroom while they're asleep, steal all of their Harry Potter merchandise and throw it onto a bonfire before they wake up. Or, at the very least, encourage them to think about scaling back their obsession, just enough that they wouldn't be the prime suspect if one of their heroes were to mysteriously go missing.
WWE fans can be just as bonkers of course. If you haven't met any in real life then you've probably seen one in the front row of a live show, draped in a full cosplay outfit and looking as though the prospect of their favourite wrestler losing a match might be enough to tip them over the edge.