The existence of such 'percy weasley abused fanfiction' could also be due to the sheer freedom of the fanfiction realm. There are no strict editorial guidelines like in official publishing. Writers can let their imaginations run wild, and sometimes that results in extreme interpretations. Also, they may be influenced by other dark fanfictions they've read and want to create something similar but with Percy Weasley as the focus, whether it makes sense in the context of the original character or not.
One reason could be his ambition clashing with his family values. Percy is often very career - driven in the original story. Maybe in the fanfiction, his pursuit of success at the Ministry of Magic leads him to make decisions that isolate him from his family, ultimately causing him to run away. For example, he might be given an important assignment that goes against the Weasley family's stance on certain magical politics.
One reason could be to explore the darker side of Percy's life. His story is mainly about his heroics, but this could show what he endures at home. It also might be to create more depth to his character by showing how he copes with such a difficult situation.
It could also be a form of catharsis for those who have experienced abuse in real life, though this is a rather controversial way of dealing with it. By writing or reading about abuse in a fictional context, they may feel they are processing their own feelings, but it can also be triggering for others. Another reason might be that some writers simply want to create shock value to get more attention for their work.
Some people might create it out of a desire for shock value. They want to stand out from the normal, positive Pokemon fanfiction by creating something extreme.
One possible reason could be the exploration of dark and complex emotions. Some writers might want to dig deep into the characters' psyches by putting them in extreme situations like abuse. Another reason could be a way to add drama and tension to the story. By having such a difficult and controversial element, it can create a lot of emotional impact.
Well, some writers may be trying to create a more 'gritty' or 'realistic' version of the Naruto universe in their eyes. They might think that adding an element of abuse to Sakura's story can add more depth and drama. However, they may not fully consider the negative impact it can have on the character and the fans who love her. Also, it could be a way for the writer to express their own darker emotions or experiences through the fanfiction, although this is not a very healthy or appropriate way in this context.
It might also be a way for some writers to express their own experiences or feelings about abuse in a more fictional and somewhat safer context. They use the familiar Twilight world and characters to tell a story that might be cathartic for them. However, this doesn't make it any less disturbing for some readers. Also, some writers might just be attracted to creating shock value with such a dark concept in a popular fandom.
One reason could be a desire for a darker, more edgy take on the characters. Some fans like to explore the 'what if' scenarios that are completely different from the original narrative. They might want to add more conflict and drama to the relationship between Legolas and Thranduil.
Some writers might be exploring dark themes for the sake of drama. They think it can create intense emotions and complex character arcs.
One reason could be that some fans want to explore the darker aspects of a character's life in a fictional and extreme way. They might think it adds depth or a different perspective to the character. But this is a rather controversial approach.