Obviously, Harry himself is a central character. Hermione and Ron are also very likely to be in it as his closest friends. Dumbledore may also play an important role, as he often guides Harry in the original stories. He could be the one Harry confides in about his new ability to see the future.
Well, one plot could be that Harry sees the future and tries to prevent a major disaster at Hogwarts. He might see Voldemort's new plan to attack the school in a different way and then he starts to gather his friends to set up defenses in advance.
It could be a new dark wizard that they see in the future. Maybe someone who was overlooked during the fight against Voldemort but has been secretly gathering power.
One possible plot could be that they see a future where the wizarding world is in great danger again. So they start to train young wizards secretly to prepare for the upcoming threat.
It might make his relationships more strained. For instance, if he sees a future where his friend gets hurt, he might become overprotective, which could annoy his friend. His friends might not believe him at first either, causing some friction.
Well, initially, there would be some misunderstandings. The X - Men are used to dealing with mutants and their powers, while Harry is from a world of wizards. But as they get to know each other, they would start to interact more smoothly. Harry could use his future - seeing ability to warn the X - Men about upcoming dangers. The X - Men, like Wolverine, might be a bit skeptical at first but would soon come to trust Harry. Storm could be very interested in Harry's magic, and they could exchange knowledge about their different abilities. Cyclops, as a leader, would try to incorporate Harry into their plans based on his visions.
Maybe it's due to some sort of restriction. For example, if he is in an environment where access to such non - official fictional works is blocked, like in a strict educational institution or a place with limited media access.
His closest ally could be Professor X. Since Professor X is also very much about using his mental powers for good and has a great understanding of powers and how to control them. He would likely see the potential in Harry and help him develop his future - seeing ability further while Harry could use his ability to help Professor X in his plans for mutant - human coexistence.
Well, his ability to see the future would likely cause a great deal of chaos. In the X - Man world, there are already so many complex relationships and power struggles. Harry's foresight could disrupt the balance. For example, he could see the rise of a new mutant threat and try to stop it in ways that the X - Men or the Brotherhood might not agree with. It could also lead to him being hunted by those who fear his power.
Sakura is the central character. In addition, there could be a mysterious old woman who seems to know more about Sakura's power than she does herself. This old woman could be a guide of sorts, giving Sakura hints about how to control and understand her visions better. There might also be a rival character, perhaps a jealous classmate named Akiko, who tries to undermine Sakura because she's jealous of the attention Sakura gets due to her unique ability.