Well, it would probably change the entire course of the story. Many characters' arcs and plotlines would be drastically different.
If Harry died there, it could lead to a sense of hopelessness among his friends and allies. The fight against Voldemort might lose its key figure and inspiration. Also, it might cause other characters to step up and take on roles they otherwise wouldn't have.
It would be a huge shock and could result in a darker and more desperate tone for the rest of the fanfic. Maybe new heroes would emerge, or the wizarding world could fall into total chaos without Harry's presence.
Well, there could be new secrets revealed about the Hall of Prophecy. Maybe a young wizard stumbles upon a prophecy that was lost for centuries and has to figure out what to do with it.
It could lead to a very emotional and dramatic story. Maybe her friends and family would be devastated and go on a quest to honor her memory.
It could show their relationship growing stronger. For example, in the dangerous and mysterious Department of Mysteries, Harry might rely on Ginny's quick thinking and courage more than ever. This could make him see her in a new light and deepen his feelings for her.
If Harry arrives at Hogwarts as a Snape fan, it would be quite interesting. He would probably idolize Snape's knowledge of magic, especially in Potions. So, he'd be more dedicated to learning in that class. This could also mean that he'd be more interested in Snape's personal projects or research. Harry might end up being Snape's favorite student, which would be a huge shift from the original story. And this new relationship could lead to different alliances within Hogwarts, as Harry's friendship with Snape could influence how he interacts with other houses and characters.
If Harry looked like Lily in fanfic, it might change how other characters interact with him. It could also have an impact on his self-perception and the way he navigates the magical world.
If Undyne won, it could lead to a major shift in the story's direction. Maybe she'd become a hero figure and inspire others.
They might be quite surprised. Some Slytherins could see it as a chance to taunt Harry's friends, while others might actually feel a bit of sympathy, even if they don't show it openly. After all, bullying is not something to be taken lightly.
In such a fan fiction, there would likely be a great deal of shock among the characters. Harry's friends might feel betrayed or confused at first. Dumbledore would probably have to re - evaluate his plans regarding Harry. And Snape himself would have a whole new set of responsibilities and emotions to deal with, having his relationship with Harry out in the open.
Perhaps in the fanfic, Harry is lured into a trap in the Department of Mysteries. Once there, Death Eaters could torture him to find out how he was able to resist Voldemort's attempts to possess him. They might also be interested in the connection between Harry's mind and Voldemort's, thinking that by torturing Harry they can gain some sort of power over that connection.
One interesting storyline could be about a new mystery uncovered within the Department of Mysteries that the original characters didn't encounter. For example, a hidden chamber filled with ancient magic that has the potential to either save or destroy the wizarding world. Another could be a story where a character gets trapped in a time - loop within the Department, reliving the same events over and over until they figure out how to break free. There could also be a fanfiction where a young, unknown wizard or witch is secretly working in the Department and discovers a plot against Hogwarts by a group of dark wizards who are using the Department's resources.