At first, Hermione would be heartbroken. She has shared so many experiences with the Weasleys. However, her strong will would soon take over. She would probably focus on proving her innocence if that was the cause of the betrayal. She might also try to find a way to reverse whatever situation led to the Weasleys' betrayal. If it was a matter of the Weasleys' own wrong beliefs, she would try to show them the truth, but if they refused to listen, she would distance herself from them while still remaining true to her own values and the greater good.
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.
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 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.
There are quite a few fanfictions around this idea. In some, it might be Ron's brothers realizing Hermione's intelligence and kindness and developing feelings. For example, George might see her business acumen and be intrigued. It's a really interesting concept as it adds a new dynamic to the existing relationships in the Harry Potter universe. Hermione is such a strong character and the Weasleys have their own unique personalities, so the fanfictions can be really diverse in how they approach this.
This fanfiction could be exploring the relationship between the Weasleys and Hermione in the context of the Harry Potter universe. It could involve things like Hermione spending time at the Weasley home, the Weasleys teaching Hermione something new about magic or wizarding traditions, or it could be a story that delves into how Hermione fits into the Weasley family's social circle.
It could be about the Weasley family's relationship with Hermione in the context of fan - created stories. Maybe it shows how they interact, support or have unique adventures together in the fanfiction world.
I'm not sure if it's popular. It depends on various factors like how well - written it is, how unique the concept is within the large Harry Potter fanfiction community, and how much it gets promoted. There are so many fanfictions out there that it can be hard for any one to stand out.