One possible reason could be a misunderstanding. Maybe there was a miscommunication about something important, like a plan to fight against the Dark Arts. For example, if the Weasleys accidentally left Hermione out of a crucial part of the plan, she might be very angry.
It could also be because of a difference in values. If the Weasleys have a more laid - back approach to something like schoolwork or following rules, and Hermione, being a stickler for rules and academic excellence, might get mad at them for their lackadaisical attitude.
Perhaps Ron Weasley said or did something really hurtful to Hermione, and she extends her anger to the whole Weasley family because they are so close - knit. Like if Ron made a comment about her Muggle - born status in a negative way, Hermione would be justifiably mad at him and might be mad at the rest of the Weasleys for not correcting him right away.
Well, in many fanfictions, Percy might be seen as too ambitious and career - focused. He could have made choices that put his job at the Ministry above his family. For example, he might have supported Ministry policies that the rest of the Weasleys disagreed with, like their stance on Harry Potter or how they were handling the growing threat of Voldemort. This could lead to the Weasleys being mad at him for seemingly choosing the wrong side or not standing by the family values.
Well, they could start with an honest conversation. The Weasleys could sit down with Hermione and ask her what's wrong. For example, Ginny could take the lead and say, 'Hermione, we know you're mad at us. Let's talk about it.'
The Weasleys could also be the ones to reach out first. They might realize that Percy was in a difficult situation at the Ministry and that he didn't mean to cause them harm. So they forgive him and they all work together to face whatever threats are out there, like Voldemort's return.
One possible reason could be jealousy. Maybe one of the Weasleys develops romantic feelings for Hermione and the others don't approve or also have feelings for her. Another reason might be related to her magical abilities. If Hermione has some unique magic or knowledge that the Weasleys think can benefit them or their family in different ways, they could fight over it. For example, her knowledge of ancient spells could be seen as a great asset.
It could be that in the fanfic's plot, the Weasleys have some actions that go against Hermione's principles. Say, they might be involved in some pranks that have negative consequences for Hermione's studies or personal goals, and that's why she hates them.
Well, in many such fanfictions, the Weasleys might protect Hermione by using their magic skills. For example, they could create protective spells around her when she's in danger. They might also physically stand in her way when she's facing threats, like some dark wizards. And they would use their family influence in the wizarding world to keep her safe from any kind of harm or discrimination.
One possible plot could be that the Weasleys might betray Hermione over a powerful magical artifact. Maybe they believe she has become too power - hungry in her pursuit of knowledge about it and they side with those who want to keep it away from her.
One possible reason could be jealousy. Maybe she sees the Weasleys as getting things too easily in the wizarding world compared to her own hard - earned achievements. For example, they have a big family support system that she lacks, and she might envy that.
Perhaps in this fanfic, the Weasleys have some actions that conflict with Harry and Hermione's values. For example, if the Weasleys were to make a deal with a dark wizard for the sake of their family's safety and Harry and Hermione found out. This could lead to a rift and hatred. Also, it could be related to a love triangle situation in a very convoluted way. Maybe one of the Weasleys unknowingly gets in the way of Harry and Hermione's relationship, or vice versa, which causes animosity.
Well, it could be a completely innocent and humorous story. Maybe they all got accidentally locked in a magically malfunctioning shower room at Hogwarts. And they have to work together to get out, with Hermione using her intelligence and the Weasleys' unique skills and prank - like ideas. It could be full of banter and light - hearted moments as they figure out a solution.