One horror story could be about overly possessive fans. There were cases where some fans would attack others who didn't share the same 'ship' (relationship pairing) in the Hetalia fandom. They would send mean messages and create a very hostile environment for those with different opinions.
I heard that during some fan events, there were arguments that turned physical over which character was more important or which storyline was better. It was really disturbing to see that a fandom which was supposed to be about enjoying a fun anime could lead to such aggression. People were shouting and pushing each other, all because of differences in their love for Hetalia.
One of the 'Hetalia Horror Stories' could be about a character getting lost in a haunted version of their own country. They might encounter strange apparitions that resemble historical figures in a distorted way, which adds to the horror as they try to find their way out.
Perhaps a story where a character is being haunted by the ghosts of all the lives lost during a major historical event related to their country. These ghosts keep tormenting the character, making them relive the pain and suffering over and over again.
A frequent theme in 'fandom horror stories' is the sense of entitlement. Some fans feel they are entitled to special treatment or access just because they are fans. This can lead to them doing unethical or scary things, like hacking into a star's personal accounts to get exclusive content. Also, there is often a theme of isolation. Fans get so deep into the fandom that they isolate themselves from real - world relationships and this can have some very strange and sometimes horror - like consequences.
The overzealous theory - fans are also a common type. They can be so pushy with their ideas that it scares off others who just want to enjoy the fandom casually.
One horror story could be about a really intense shipping war within the Homestuck fandom. Fans of different ships were so aggressive towards each other that it created a really toxic environment. People were sending mean messages and threats just because of their preferred character pairings.
There are horror stories where the magic in Equestria goes horribly wrong. Like a spell that was meant to do good but instead creates a nightmarish dimension where ponies are constantly in pain and fear. This is terrifying as it shows how the very thing that usually brings harmony can be so destructive. Also, stories about ponies being haunted by unseen forces that slowly drive them mad are quite common and spooky.
Well, there was a 'fandom horror story' in the gaming fandom. A player was so into an online game that he believed he was actually a character in the game. He started to act out the game's violent scenarios in real life, which was really terrifying for the people around him.
One scary Hetalia story could be about the wars. For example, the chaos and destruction during World War II as depicted through the Hetalia characters can be quite terrifying. The characters facing the brutalities of the battlefield, the fear in their eyes, and the uncertainty of survival are all elements that make it a scary narrative.