Over time, they would probably come to accept Harry for who he is. Their friendship could become even stronger as they support Harry through his new challenges. They might even start to fight for werewolf rights within the wizarding world because of Harry's situation.
Well, it depends on how the fanfiction portrays it. In some cases, his friends could turn against him completely. They might see him as a danger to the wizarding world. But in more positive portrayals, they would see this as just another challenge for Harry to overcome. They would be there for him, but it would be different. For instance, they might have to help him find new ways to do magic since the vampire bite could potentially affect his magic in some ways. Their relationship would be a mix of loyalty and a new kind of understanding as they all deal with this unexpected change in Harry.
On the other hand, Dumbledore could use Harry's new situation as a werewolf to his advantage in the fight against Voldemort. He might encourage Harry to embrace his werewolf side as a source of strength. This could lead to a more complex and strategic relationship, where Dumbledore sees Harry as an even more powerful weapon against the Dark Lord, but also has to balance the risks associated with Harry's new condition.
Hermione might become more protective of Harry. She would probably start researching ways to reverse the transformation or at least manage it better. Their relationship could become a bit strained as Harry may feel ashamed of his new state and try to push Hermione away at first.
Her relationship with Harry and Ron could become strained. They might be afraid of her new werewolf side at first. But over time, they could come to accept her and even help her in her struggle. For example, Ron might use his family's knowledge of magical creatures to find ways to ease her transformation.
Dumbledore would be very concerned about Harry's future. He would try to guide Harry in controlling his new abilities. Their relationship might shift to a more teacher - student dynamic focused on this specific issue. Dumbledore could also use Harry's situation to teach the wizarding community a lesson about acceptance. He might encourage Harry to be open about his condition and show that being bitten doesn't make him any less of a hero. This would be a big change from their previous relationship which was more about the overall fight against Voldemort.
It could make his friends a bit more cautious around him at first. Since the shadow magic is so different and potentially dangerous, they might be worried about what Yugi could do accidentally. But as they see Yugi learning to control it, their trust in him would be rebuilt and their relationship could become even stronger.
Harry might be more protective of his friends in the new timeline. He has seen what can happen to them in the future, so he'll do everything he can to keep them safe. With Hermione, he could encourage her to pursue her interests more freely, knowing how important her knowledge and skills will be. And with Ron, he may try to boost his confidence from the start, so Ron doesn't feel overshadowed as he did in the original timeline.
Well, in Slytherin, Harry could end up being one of Snape's top students. This might lead to a more positive relationship. Snape might see Harry as a chance to redeem the Slytherin image. He could start to trust Harry more and share some of his knowledge about dark magic in a more open way, which was not possible when Harry was in Gryffindor.
They might become closer friends. Cedric could be grateful to Harry for trying to save him during the Triwizard Tournament, and Harry would be glad that Cedric survived. They could start sharing their experiences and knowledge about magic more often, and perhaps even train together to become better wizards.
In a Slytherin - Harry fanfiction, Hermione may initially distance herself from Harry. But when she realizes that Harry is still the same person deep down and that he's using his Slytherin traits for good, like using his ambition to excel in difficult subjects and his cunning to outsmart bullies. She might start to see the value in the Slytherin house and their relationship could become more of a partnership where they both learn from each other's different approaches to magic and life at Hogwarts.