Harry might express his jealousy by being short - tempered around Krum. For example, when Krum tries to talk to him about Hermione, Harry could give curt responses.
Harry might be really confused at first. He doesn't understand why Hermione is acting so strange. He might try to talk to her about it, but if Hermione is being stubborn, he could get frustrated. He could also be a bit oblivious and just think Hermione is being overprotective as a friend.
The jealousy in this fanfiction scenario can have a complex impact on their friendship. Hermione's pride in her academic achievements is a big part of her character. When Harry gets good grades, she might feel like she's losing her 'edge'. This could make her distance herself from Harry. But as the story progresses, they'll realize that they each have their own strengths and weaknesses. Harry's success in grades doesn't diminish Hermione's intelligence, and they'll learn to support each other again, strengthening their friendship in the long run.
A possible plot is that during a Triwizard Tournament event where Krum is competing and Hermione is cheering him on, Harry feels a pang of jealousy. He begins to train extra hard for the next task, not just to win the tournament but also to impress Hermione. Meanwhile, Hermione is oblivious to Harry's jealousy and thinks he's just being his usual competitive self.
Often, Ginny will try to insert herself between Harry and Hermione. She might constantly try to get Harry's attention when he's with Hermione or try to exclude Hermione from activities that involve Harry. In some fanfictions, Ginny might even spread rumors about Hermione to try and drive a wedge between her and Harry.
In these fanfictions, Ron's jealousy is portrayed in various ways. Sometimes he'll try to interfere with Harry and Hermione's time together. He might create small misunderstandings between them on purpose. Other times, he'll show his jealousy more subtly, like by looking sad or disappointed when they share a private joke or moment. His body language can also give it away, like crossing his arms and frowning when they are being friendly with each other.
Hermione would be a great addition. She could provide her vast knowledge of magic and books to help Harry and Krum in their adventures. For example, she might research spells or potions that are needed to overcome certain obstacles.
His jealousy might make him a bit withdrawn from Bill. He could be less friendly and more distant, which could cause some tension between them. As for his relationship with Fleur, he might act a bit awkward around her, not really knowing how to handle his feelings.
Well, Harry is known for his loyalty to his friends. So when they try to testify against him (maybe under some kind of spell or false evidence), he could get really angry. He might start pacing back and forth in the courtroom, his fists clenched, and then turn to his so - called friends and say in a cold, angry voice 'I thought you knew me better. How could you believe these lies?' His anger would be a mix of betrayal and the general unfairness of the trial situation.
One possible reason could be that Dean is better at something that Harry secretly wishes he was good at. For example, if Dean is really popular among their peers and Harry feels overshadowed. Another reason might be related to a girl they both like. Maybe the girl shows more interest in Dean, and Harry can't help but feel jealous.
One possible reason could be Fleur's unique charm. She is part - Veela, which gives her an alluring quality that might make Harry feel insecure. Another reason might be her skills. If in the fanfiction she is shown to be extremely talented in magic, especially in areas where Harry struggles, it could trigger his jealousy.