Well, it could be related to Percy's past actions. If he has a history of being unreliable in the eyes of the character rejecting him, that would be a valid reason. For instance, if he has broken promises in the past. Or perhaps there are external factors at play. Maybe the family of the person rejecting Percy doesn't approve of him, so they influence the decision. Another aspect could be that Percy is too different in terms of values. If he values adventure and risk - taking above all else and the other character values stability and safety, it can lead to a rejection.
Family drama. The Weasley family has its fair share of chaos. His relationship with his family members, especially after some of the disagreements he had, could be a source of emotional stress that manifests as migraines. For example, his estrangement from his family during a certain period in the books could have taken a toll on his mental well - being.
One possible reason could be that it doesn't follow the established lore of the Twilight universe. For example, if it misrepresents the nature of the imprinting concept which is quite central to the series. Another reason might be poor writing quality, like having numerous grammar and spelling mistakes. Also, if it goes against the general tone of the Twilight series, say being too dark or violent when the original is more focused on a certain type of romantic and fantastical tone, it could be rejected.
Perhaps Draco has been bullying some of Percy's friends or younger students that Percy feels responsible for. In fanfiction, the relationships can be tweaked a bit. Percy might be more hot - headed in some versions and not put up with Draco's pure - blood supremacist attitude towards those he deems as 'lesser' students. So he sends the Howler as a strong warning.
One possible reason could be that Hermione is too focused on her studies and career goals in the wizarding world. She might see a relationship with Harry as a distraction. Another reason could be that she has different values when it comes to love. Maybe she wants someone more like her, who is more into books and intellectual pursuits all the time, while Harry is more action - oriented.
Annabeth is a very determined and strong - willed character. In her mind, Percy is part of her 'territory' because she has fought beside him and for him. She may feel that she has a claim on him, and this sense of ownership makes her territorial.
One possible reason could be that there are cultural differences between Harry and the elf. Elves might have different values and traditions when it comes to relationships. For example, their society might have strict rules about mating or partnering with non - elves.
One reason could be false accusations. Maybe someone frames Jaune for a serious offense he didn't commit, like cheating in an important exam or stealing valuable items from the school. Another reason might be his inability to keep up with the academic or combat requirements. If he fails too many classes or consistently underperforms in combat training, the school might decide to expel him.
Perhaps the fanfiction is following a specific plot arc that doesn't naturally involve Stiles. Like if it's a story about a new villain in town and the existing characters are dealing with it in a way that doesn't require Stiles' skills or presence. Also, some writers might be influenced by popular trends in the fandom that don't feature Stiles, and they go along with that to attract more readers.
If the fanfiction goes against the core values of the Naruto series, like turning a heroic character into a completely evil one without a proper explanation, it might be rejected. Also, if it plagiarizes other works, that's a definite no - go.
One reason could be a weak plot. If the story doesn't have a clear and engaging plotline, it might get rejected. For example, if it's full of random events that don't lead anywhere. Another reason is poor writing style. If the grammar, punctuation, and sentence structure are all over the place, editors won't be interested. Also, if the characters are not well - developed, like they lack depth or motivation, the novel may be rejected.