Some people might create it out of a desire to explore dark or 'what - if' scenarios that are completely opposite to the normal relationship in the original work. It could also be a way for them to experiment with different types of conflict in writing, though it's not a very positive or healthy way.
It might exist because some writers like to push boundaries. They may think that by creating a scenario where Annabeth abuses Percy, they can create a unique and edgy story. But this completely distorts the characters as they are portrayed in the original series. In the 'Percy Jackson' books, their relationship is based on mutual respect, friendship, and partnership. So, this kind of fanfiction is a deviation from the essence of the story and is likely created by those who want to be different at the expense of the integrity of the characters.
One possible reason could be a misinterpretation of the characters. Maybe the author had a different view of Annabeth and Percy's relationship and took it to an extreme. Another reason could be a simple attempt to shock readers. However, this is not in line with the positive nature of the 'Percy Jackson' universe. Fanfiction should generally aim to enhance or expand on the positive aspects of the original, not introduce such negative and disturbing concepts.
Some fans might write this type of fanfiction as a form of catharsis. They may have had certain emotions or ideas related to the characters that they want to express in a more extreme way. Also, it could be a way to explore the moral and ethical boundaries within the Percy Jackson world. By having Annabeth torture Percy, it forces the readers and the writer to think about what is right and wrong in that fictional context, and how the characters would be affected by such actions.
It could be that the writer wants to explore the darker side of human nature within the context of these characters. By having Annabeth cheat with Zeus, they can delve into themes like betrayal, jealousy, and the breakdown of relationships. Additionally, some might be doing it as a form of rebellion against the 'perfect' relationship that Annabeth and Percy seem to have in the original, wanting to add a bit of chaos and realism to the fictional world.
Perhaps there are some who have a darker side to their creativity and don't fully consider the implications of writing about abuse. But this kind of fanfiction should not be encouraged as it goes against the positive nature that most fanfiction communities strive for.
There could be several reasons for the existence of such fanfiction. Firstly, it might be a form of creative exploration for those who want to test the boundaries of the characters' personalities. They may think that by putting Inuyasha in an 'abusive' role, they can dig deeper into his character flaws. Secondly, it could be an attempt to create a contrast. Since the original relationship between Inuyasha and Kagome is mostly positive, showing an abusive side can create a sharp contrast. However, this kind of fanfiction often goes against the general perception and liking of the majority of fans.
Some people might be exploring the darker side of human nature through these characters. They want to see how extreme situations can play out between Sasuke and Sakura.
Some writers might create this type of fanfiction for shock value. They know that the original relationship between Rick and Morty has a certain dynamic, and by making it into an abusive one, they can get a strong reaction from readers. Also, it could be a form of expressing their own dark interpretations of power dynamics within the show.
Some people might create it just for shock value. They know that the original relationship between Goku and Chi - Chi is loving, so by creating something so opposite, they can get a reaction from readers.
It could also be that in the fanfiction, Percy is given a new power or ability that Annabeth sees as a threat. Or perhaps Percy is made to side with someone Annabeth dislikes, causing her to 'hate' him in that fan - created story. This shows how different plot elements in fanfiction can change the dynamics between characters.
Perhaps the fanfiction is set in an alternate universe where something has happened to change Percy's feelings towards Annabeth. For example, if there was a betrayal in the fan - created story that made Percy turn against her.
Well, one possible reason could be that Percy made a really stupid decision without consulting Annabeth first. Like, if he went off on a dangerous mission on his own when they were supposed to be a team. Annabeth is a very strategic person and she might feel betrayed or extremely frustrated by such actions.