There are those who create such fanfiction because they want to explore alternative storylines. If Ginny is portrayed negatively, it can open up new paths for Harry and Hermione's relationship to develop. But it's a divisive practice as many fans are attached to the original characterizations and don't appreciate the bashing.
Some writers might do it for the sake of creating drama. By making Ginny a 'villain' of sorts, they can add more conflict to the relationship between Harry and Hermione.
Some people write it because they simply have different ideas about who Harry should be with. They might have a favorite character other than Ginny and want to explore a relationship between Harry and that character. Maybe they didn't like how Ginny was written in the original books and feel the need to rewrite the story in a way that suits their view.
One example could be a fanfic where Ginny is portrayed as overly jealous and it causes rifts between Harry and Hermione. Another might be a story where Ginny's actions are misconstrued in a way that makes her seem like a hindrance to Harry and Hermione's friendship. However, bashing characters in fanfiction can be controversial as it goes against the original spirit of the story for many fans.
One possible reason could be for the sake of creating drama. In many fictional works, conflict is key to driving the story forward. By having Ginny hate Hermione, it can stir up all sorts of situations, like jealousy over Harry perhaps. Ginny might be jealous of Hermione's close friendship with Harry, which could lead to some interesting storylines.
Well, a possible reason is that they have a different interpretation of Ginny's character. Maybe they didn't like how she was developed in the original series and so they write fanfiction to rewrite her in a way that suits their view. For example, if they thought she was too one - dimensional in the books, they could make her more complex in a negative way in their fanfiction. Also, it could be a way for them to express their own creativity by taking a well - known character and turning her into something different, even if it means bashing her.
Some writers do it because they want to create a more edgy or different take on the story. They might think that by making Molly a less - than - perfect character, they can add more conflict to their fanfic.
Some people might write it because they want to explore alternative character dynamics. They may feel that Hermione's character in the original was too perfect and want to see how the story would change if she had more flaws.
Some people might write it because they simply don't like Hermione's character in the original books. Maybe they find her too perfect or too overbearing and want to create a different version of the story where she's not so dominant.
Some people write 'harry hermione ron bashing fanfiction' because they want to explore different perspectives. Maybe they think the trio is too idealized in the original series and they want to show their more human, flawed sides.
Maybe the writers want to deviate from the typical 'happily - ever - after' story. They might feel that in the wizarding world, relationships are complex and not always smooth - sailing. So, the 'Ginny breaks Harry' plot allows them to explore more realistic relationship dynamics within the context of the Harry Potter universe.
It could be a way to explore Ginny's character more deeply. By having her stalk Harry, it shows her determination and the strength of her feelings for him. It also gives the writer a chance to show how she might deal with her emotions privately.