He might flee because fanfiction can sometimes distort his character. In some fan - made stories, his personality, values, or relationships could be changed in ways that are untrue to the original. For instance, if a fanfiction makes him act cruelly when he's supposed to be kind - hearted.
In fanfiction, Harry could flee Britain due to a sense of disillusionment with the wizarding world there. He has been through so much trauma and has seen the flaws in the system. For example, the way the Ministry handled the threat of Voldemort in the past was often inept. He might also be seeking a place where he can explore magic in a different way, free from the traditional constraints of the British wizarding community. He may want to start anew in a place where no one knows him as 'The Boy Who Lived' and can just be Harry, an ordinary wizard exploring his magical abilities.
Perhaps they fear that fanfiction could deviate too much from the original themes and values of the Harry Potter series. The official story has a certain moral and ethical framework, and fanfiction might distort it.
It could be that the Harry Potter brand wants to control the narrative more tightly. Fanfiction can sometimes take the story in directions that the official creators don't like. So, to maintain a certain image and story integrity, they might be discouraging fanfiction.
One reason is copyright infringement. If the fanfiction uses too much of the original Harry Potter material without permission, it can be considered forbidden. Another reason could be that it contains disturbing or immoral content that doesn't align with the family - friendly nature of the original series.
One reason could be copyright. The creators and rights holders of Harry Potter want to protect their intellectual property. Fanfiction can sometimes blur the lines of ownership and might use elements of the story in ways that aren't authorized.
One reason could be copyright issues. The creators of Harry Potter own the rights to the characters and story, and fanfiction often uses these without permission.
Often, they flee because they are in danger. For example, in some fanfictions, Voldemort might be after them for some reason, like a new kind of magic they possess that he wants for himself.
Perhaps he's following a lead related to his parents. There could be some secrets about his family that are hidden in America. He goes there to uncover the truth and learn more about his family's past that might not be available in the UK.
Because fanfiction is a way to keep the magic of Hogwarts alive. Harry Potter, being the hero of the story, would understand the importance of that magic and want to protect the creative works that continue to explore Hogwarts.
For entertainment. Just like anyone else, Slytherin students would be interested in exploring different stories set in the Harry Potter universe.