Hermione might seek revenge. Given her intelligence and magical abilities, she could use her skills to get back at Harry and Ron for their betrayal. This could lead to a big rift in their friendship and even endanger their common goals in the wizarding world. She might also side with other characters who are against Harry and Ron, changing the whole dynamic of the story.
In some fanfictions, it could be a misunderstanding that spirals out of control. Hermione and Ron misinterpret one of Harry's actions. For instance, Harry might be trying to protect them in a secret way, but it looks like he's up to something bad. Their lack of trust then grows, and they end up betraying Harry, perhaps by not coming to his aid when he really needs them, which could have serious consequences for Harry.
She might become more distrustful. After being betrayed, it's natural for her to question the motives of those around her, even her closest friends.
She might become more distrustful. After being betrayed, it's natural for her to have a hard time trusting others again.
One possible plotline could be that Ron and Hermione are influenced by dark magic or a powerful enemy who manipulates them into betraying Harry. For example, they might be under the Imperius Curse. Another could be that they misunderstand Harry's actions or intentions, leading them to believe he has gone to the dark side, so they turn against him in an attempt to 'save' the wizarding world. Maybe they are jealous of Harry's fame and power growing too much, and this envy festers until they decide to betray him.
He might start to compare the real Hermione with the versions in the fanfiction, which could cause some confusion in their real - life relationship.
Well, for Harry, it would be a huge emotional blow. He trusts Hermione deeply, so her betrayal could make him question his own judgment. It might also make him more isolated as he loses one of his closest allies. For the wizarding world, if Hermione was on the wrong side, it could lead to chaos as she is very intelligent and powerful. Her knowledge of spells and magic could be used against the good side.
Well, it could be really awkward for him. He might feel a bit strange knowing that people are writing fictional stories about his two best friends. He could also be a bit protective and might not like the way some fanfictions portray Ron and Hermione. Maybe he'll be amused too, depending on the content of the fanfiction.
There could be a break in their friendship. Ron might realize he made a mistake, but Hermione might not be so quick to forgive. It could take a long time for them to get back to the way they were, if they ever do. They might have to go through a lot of awkward moments and difficult conversations.
It could be that a prophecy reveals something that makes Ron and Hermione think Harry is a danger to the wizarding world. They might decide to betray him in order to protect the greater good. However, as time goes on, they could realize their mistake. But by then, the damage to Harry's trust would already be done, and he would have a hard time forgiving them.
At first, Harry might be confused. He would try to figure out what went wrong. He might search his memory for any signs that could have led to this betrayal. Then, he would likely experience a range of emotions from sadness to rage. Depending on the nature of the betrayal, he could either try to win them back by showing them the truth or decide that they are no longer worthy of his friendship and focus on his own path, maybe even leaving the wizarding world for a while to clear his head.