One possible reason could be jealousy. Maybe Ginny is jealous of Hermione's intelligence or her close relationship with Harry. So, out of spite, she uses the slur.
Another reason might be related to family or group loyalty. If there were some tensions between pure - blood families (the Weasleys are pure - bloods) and Muggle - borns like Hermione, Ginny could be influenced by some radical family members or ideas within the wizarding community in the fanfiction and use the term without really thinking about how wrong it is.
It could also be due to some misunderstanding. For example, if there was some false rumor going around about Hermione that made Ginny believe something bad about her. And in a moment of anger, Ginny lashed out with that awful word.
One possible reason could be that he's been influenced by some dark magic or a spell that makes him act out of character. Another reason might be extreme jealousy, say if Hermione is getting more recognition in the wizarding world than him for some time and he lashes out in a moment of weakness.
Well, perhaps in the fanfiction, Harry might feel that Hermione understands him on a more profound level when it comes to his role as the Boy Who Lived and his struggles with the wizarding world's future. Ginny, while she loves Harry, might not be as involved in those complex aspects. Also, the author might write it so that Hermione and Harry have a shared vision for the future of the wizarding community that Ginny doesn't share, leading Harry to choose Hermione.
One possible reason could be to create drama. Fanfiction often takes the existing relationships and twists them for the sake of a more engaging story. Maybe the author wants to explore how Hermione would react to such a hurtful comment from Ron, and how it would impact their friendship or potential romantic relationship.
In some fanfictions, it could be related to a power struggle within the wizarding world. If Hermione was seen as a threat to Ginny's family or her own standing in the magical community, Ginny could be pushed to the edge. Also, if there was a rift in their friendship over ideological differences, like Hermione's more logical and rule - based approach clashing with Ginny's more impulsive and instinctive nature in a very extreme way, it might lead to such a tragic outcome.
The idea of subverting the expected relationships is appealing. Instead of the more common pairings, this pairing offers a fresh take. It also allows for a deeper exploration of the characters' personalities. Since they are so different, seeing them come together in a romantic way can be really interesting for fans who want to see new aspects of their favorite characters.
One possible reason could be the strong intellectual bond Harry has with Hermione. They've been through so many adventures together, solving mysteries and facing challenges. Their shared love for knowledge and learning might make Harry realize he has a deeper connection with Hermione compared to Ginny.
The implications would be quite serious. Firstly, it would shock the readers who are familiar with their relationship. Hermione would be deeply hurt, and Ron would be seen as a character who has lost his moral compass. It might also change the power dynamics in the story. Hermione could become more withdrawn or vengeful, and Ron would have to face the consequences of his actions, either through guilt or the backlash from other characters. This could also lead to a divergence in the overall plot, with the focus shifting to their damaged relationship and how they might or might not overcome it.
One reason could be that the fanfiction is set in a different universe where the characters' personalities are slightly altered. So, this 'new' Harry just doesn't click with Ginny in that version. For instance, if the fanfic is a darker take on the story, Harry might be more jaded and not open to a relationship with Ginny.
In some fanfictions, Ginny may reject Harry because she wants to focus on her own personal growth. She might feel that a relationship with Harry at that time would hold her back from achieving her own goals, like becoming a great Quidditch player or an accomplished witch in her own right. So, she decides to reject him to pursue her own dreams first.
In some fanfictions, this incident could be a turning point for Hermione. She might decide to focus more on her studies and magic skills, distancing herself from Ginny and those who tolerate such slurs. This could then lead to her achieving great things on her own, away from the drama, and eventually making Ginny realize the mistake she made.