The characters would change in many ways. Harry Potter, who has already faced so much, would become more of a survivalist. He might be more willing to take risks that he wouldn't have before. Hermione would likely turn into a strategic mastermind, thinking several steps ahead to counter the chaos of the apocalypse. Ron, on the other hand, would probably develop a more serious side. No longer could he rely on just his loyalty and friendship; he'd have to be a fighter. Neville, who has shown great courage in the original series, would become a symbol of hope, inspiring others to keep fighting. And the villains, if any are still around, would either try to take advantage of the apocalypse or be forced to side with the heroes in order to survive.
The characters around Harry would likely change. Some minor characters might become more important, and some major characters could be sidelined. For instance, Neville Longbottom could become the main hero instead of Harry in some scenarios.
The tone would become much darker. Instead of the usual heroic and somewhat light - hearted adventures, there would be a sense of dread and unease. The magic would likely have a more sinister edge to it.
The story would change drastically. The whole dynamic of the wizarding world would be different. Instead of fighting dark wizards with spells, Harry would be dealing with the implications of being a genie. His relationships with other characters would shift as they would now see him as a being with the power to grant wishes.
The story would be completely transformed if Harry Potter becomes a ghost in fanfiction. Firstly, the way he experiences the wizarding world would be novel. He could float around Hogwarts, seeing things from new angles. His relationship with Hermione and Ron would become more complex. They would have to deal with the fact that their friend is no longer fully alive. In terms of the overall plot, the fight against evil could take a different turn. Harry as a ghost could perhaps access areas that were previously off - limits to the living, like certain dark corners of the Forbidden Forest. This could lead to new discoveries about dark magic or ancient secrets. His new form could also attract the attention of other supernatural entities in the wizarding world, leading to new alliances or conflicts that weren't possible when he was alive.
The plot would become very dark. Harry would no longer be the hero, so the fight against Voldemort would likely take a different turn. Maybe Voldemort would see Harry as an ally instead of an enemy. The other characters would have to either try to change Harry back or find a new way to defeat Voldemort without Harry's help.
Maybe Harry Potter has to use his magic to fight against the apocalyptic disasters like hordes of dark creatures or a spreading deadly magic. He could gather his friends and allies from Hogwarts and the wizarding world to try and stop the end of the world.
Naruto's normally positive and upbeat character might become more hardened. He'd be more cynical after seeing so much destruction. His trust in others might be shaken, especially if he's been betrayed during the apocalypse.
His relationship with Ron and Hermione would be strained at first. Ron has always disliked Malfoy, so he'd be confused and a bit angry at Harry's newfound admiration. Hermione might be more open - minded, but still skeptical. She'd try to reason with Harry. With the Weasley family, they'd also be a bit taken aback. However, Harry's new view of Malfoy could potentially lead to a more peaceful co - existence between Gryffindor and Slytherin students in general.
The characters would change a great deal. Harry, for example, might be less of the pure - hearted hero. He could have a more cynical view of the world around him, similar to Brightburn. Hermione might be more distrustful of Harry's new - found darker tendencies. Ron could be more afraid of Harry and his powers, which would strain their friendship.
The story would change a great deal. His identity within the wizarding world would be questioned. People might be afraid of him or see him as an outcast. His ability to interact with others would be different. He might be more solitary due to his Lamia nature.