I think 'One Piece' might fit the bill. Some of its filler arcs have been really engaging and even more enjoyable than certain parts of the main story.
One filler horror story could be about a haunted doll. The doll was found in an old attic. It had a cracked porcelain face and empty eyes. At night, it would move on its own, and people in the house could hear faint giggles coming from the room where it was placed. Another could be a story of a cursed mirror. Anyone who looked into it for too long would see a distorted version of themselves and then strange things would start to happen around them, like objects moving on their own.
Filler words also play a role in the development of the narrative voice. An omniscient narrator might use different filler words compared to a first - person narrator. The choice of filler words can also change over the course of the novel as the character grows or the situation changes. For instance, a character who becomes more confident might use fewer filler words as the story progresses.
In novels, filler words can also be used for character differentiation. A nervous character might use more 'um's and 'ah's compared to a confident one. They can be a subtle tool for characterization. Moreover, in some cases, filler words can be used to create a regional or social dialect. For example, certain words might be more common in a rural setting's dialogue, which can help to paint a more vivid picture of the world in the novel.
One horror story is when a girl got lip fillers from an unlicensed practitioner. Her lips became extremely swollen and lumpy. It looked like she had sausages instead of lips. She had to go through a long and painful process to try and correct it.
I'm not sure specifically as 'true filler world novel' is not a well - known common term. It could potentially be about a fictional world that is used to fill in gaps in a story or a series. Maybe it's a made - up concept in an indie or niche genre of novels.