Ron could be a likely candidate in some fanfic scenarios. Ron has had his jealous moments in the original series, and if those feelings were amplified in a fanfic, he could do something that betrays Hermione. This could lead to Hermione begging for understanding or for things to go back to how they were, especially if she still has deep feelings for Ron as a friend or more.
Even Harry himself could be the one to betray Hermione in certain creative fanfic interpretations. It could be due to some sort of dark influence or a misunderstanding. If Harry betrays her trust, Hermione's begging would be a very emotional and complex situation. She might beg him to remember their past, their friendship, and all the things they've been through together.
A new character introduced in the fanfic could also be the one to betray Hermione. Maybe a powerful wizard who seems friendly at first but has ulterior motives. If this character does something that makes Hermione feel betrayed, she might beg for help or mercy depending on the situation. For example, if the new character frames her for a crime she didn't do, she could beg for the truth to be revealed.
Well, in certain fanfiction scenarios, Ron's jealousy could be a factor. He might feel overshadowed by Harry for so long that it finally drives a wedge between them, and Hermione, being in a relationship with Ron, gets caught up in it. Another possibility is that a prophecy or some ancient magic forces them to make choices that seem like a betrayal to Harry, but they believe they are doing it for the greater good.
Power could be a reason. If there's a chance for Ron and Hermione to gain a great deal of power by turning against Harry, some fanfictions might explore this. For instance, a new dark power might offer them something they've always desired, like the ability to reform the wizarding world in their own image. They might think Harry would oppose this, so they betray him to get what they want.
Jealousy might be a motive. If Hermione is constantly outshining them in academics or getting more praise from teachers, they could become envious and turn against her.
The White Walkers could be major antagonists. They are a huge threat in Westeros and Harry and Hermione would have to use their unique magical abilities to combat them. Their cold - based magic and army of the undead would be a great challenge for Harry and Hermione.
One possible reason could be if Harry takes a big risk without consulting her first. In the wizarding world, their adventures are full of danger, and Hermione is often the cautious one. If Harry jumps into a situation like facing a powerful dark wizard alone without a proper plan, Hermione would likely blame him for being reckless.
In some fanfiction scenarios, it could be a matter of different ideals. Suppose there is a new movement in the wizarding world that Ron and Hermione believe in, but Harry opposes it. Their loyalty to this new ideology could be so strong that they see Harry as an obstacle and decide to betray him. It could also be that they are under the influence of a powerful and evil spell that warps their minds and makes them act against Harry without their full awareness.
It could be due to a misunderstanding. Suppose Ron overhears a conversation between Harry and Hermione that he misinterprets completely. He might think they are plotting against him or don't really consider him a true friend. So in a fit of anger and hurt, he decides to betray them.
It would likely cause a great deal of strain. Harry would probably feel betrayed and angry at Hermione. Their friendship, which was once strong, would be severely damaged.
One interesting fanfic could be where Harry and Hermione visit Hermione's mom during the holidays. In this story, they might share their Hogwarts experiences with her, and she could give them some valuable muggle - world advice. It could be a heartwarming story about the blending of the wizarding and muggle worlds.
One key element is the relationship dynamic. Harry, being an orphan, might be drawn to the family atmosphere that Hermione's mom provides. Hermione, on the other hand, has to balance her loyalty to Harry and her relationship with her mother. For example, if there's a conflict at Hogwarts, Hermione might be torn between staying with Harry to solve it and going home to her mom.