Harry's reaction would depend on the nature of the fanfiction. If it's a cute, romantic fanfiction about Ron and Hermione, he might smile to himself and think it's kind of sweet. However, if it's something that distorts their characters or has a negative slant, he could get defensive. He might even try to find out who wrote it and why they would write such a thing about his friends.
Harry might react with shock. If he overhears something unexpected like Ron and Hermione confessing their love for each other, it would be a big surprise. He might stand there frozen for a moment, not knowing how to process it.
Hermione would probably be deeply hurt at first. She trusts Harry and Ron so much, and being abandoned by them would be a huge blow. But she's also very determined. So, she might throw herself into her studies even more, using her knowledge as a way to cope and also to find a solution to the situation.
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.
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.
Perhaps Harry overhears a very private and heartfelt conversation between Ron and Hermione. He might realize that their relationship has deepened in a way he hadn't noticed before. This could make Harry feel a bit left out at first, but then he would probably be happy for them. He could also use this new knowledge to be more understanding of their actions and decisions in the future.
At first, Ron might be in disbelief. He might think it's some kind of joke. But when he realizes it's real, he could be a mix of hurt and confused. He might avoid Harry and Hermione for a while, but then, as he sees how happy they are at the ball, he might start to accept it and try to be happy for them too.
Perhaps she tries to find them right away. Using her intelligence and resourcefulness, she starts to search for any clues as to where they might have gone. She could ask other friends, like Neville or Luna, if they have seen Harry and Ron. And she might be determined to bring them back, not willing to give up on their friendship easily.
Naruto would probably be quite affected. He is someone who has been through a lot of hardships in his own life, so a sad fanfiction about himself might bring back some of those difficult feelings. He could be sad for a while, but then he would likely try to shake it off and remember that it's just a story.
At first, Harry could be heartbroken. He would wonder what he did wrong to make them leave. He might try to find them and reason with them. However, if he can't reach them, he would likely turn that pain into a driving force. He would focus on his goals, like fighting against Voldemort or protecting the wizarding world, even more fiercely, because he now has to prove himself not only to the world but also to his former friends.
At the beginning, Ron would likely be in shock. He had always thought he and Hermione had a special bond. After the shock, he might become a bit bitter. However, his friends, like Harry, would probably try to cheer him up and help him see that there are other things in life. Eventually, Ron might find a new purpose in his life, whether it's in his magical studies or in exploring new parts of the wizarding world, and try to move on from Hermione.