That's actually a really good point!
I have a similar inquiry when it comes to the Rayman fandom.
Horror content; more specifically horror fanfictions.
(To specify the definition of horror fanfiction/Grimdark's from creepypastas real quick just for my point:
Grimdark: A horror centric fanfiction that takes place strictly within the universe of the characters.
Creepypasta: In relation to "Lost Episode/Haunted Game creepypasta", the story takes place outside of the ip, with most likely buildup of whatever ghost or paranormal entity that inhabits the game eventually inflicting pain into the real world.)
Think about it, the tone of the Rayman games can sometimes be akin to Coraline;
With Rayman 2 & 3 being big contenders for this.
The Kanaran's and their feasting upon Teensies flesh.
An entire robotic race that is hellbent on destroying our entire planet and reducing its people to slaves.
A dark mirror of the Glades own god; a boogyman of snake tongued deals and unimaginable riches, meant to lore you in as bait.
Although the Rayman series leans more on misty whimsy
and Tenacious D-esque sillies;
I'm still rather taken aback that the only pure horror fanfiction that's being made right now is TarotOnFire's Rayman Livid Eclipse, and Clairiphi Rayman Nightmarish.
Yeah you can have a crap ton of f@#$ fanfictions about a WALL of MOLTEN TWILIGHT'S, Rainbow Dash MURDERING Pinkie Pie; paranoid she's going to eat her, THE CANDYMARE?!
I love me some good pony gore;
These spookie ponys got the zaza
LAst I REMEMBER the root of these fics we're that ONE TIME Pinkey went a little too crazy and throwing a party with a bag of flower and rocks.
RAYMAN HAD TO RACE FOR HIS LIFE AGAINST THE LORD OF NIGHTMARES; AT RISK OF GETTING VORED; IN HOPE HIS FRIEND CLARK DOESN'T DIE FROM TETANUS AND FAIL THE ENTIRE WORLD!?
WHERE'S HIS GOLDMINE OF SPOOKY STORIES WITH HIS
Check out TarotOnFire's and Clairiphi's fanfictions
And Give Rayman the Grimdark + Fan Music zaza ya'll.