Maybe he wants to start anew. Fanfic often has its own set of pre - conceived notions and storylines associated with a particular name. Changing his name legally allows Harry to break free from those and create his own identity outside of the fan - created narratives. It could also be for protection. There might be some negative aspects in the fanfic world related to his name, such as being associated with a certain group or plotline that he doesn't like, so changing his name is a way to protect his reputation.
He might be trying to distance himself from a particular fanfic community. If there are disputes or uncomfortable situations within that community, a name change can be a way to sever ties. Also, it could be that the fanfic has created a false image of him that he wants to escape. For example, if the fanfic portrays him in a way that is not true to his real self, changing his name legally can be a step towards reclaiming his true identity.
Well, it could be due to a sense of isolation. Harry has always been somewhat of an outcast, even within the wizarding community. He might feel that he can't truly connect with others on a deep level. Additionally, in some fanfic interpretations, the author might be showing how the prophecy and his role as 'the Chosen One' has burdened him to the point of despair. It's like he has no control over his own life and destiny, which could lead to suicidal thoughts.
One possible reason could be that Harry breaks a major rule in the wizarding world within the fanfic. Snape, being a strict and by - the - book person, grounds him as a form of punishment. For example, if Harry uses dark magic without permission, Snape would surely take strict action.
One reason could be for protection. Maybe in the fanfiction, Voldemort is still a threat even after his defeat, and Harry changes his name to hide from any remaining Death Eater sympathizers. It's a way to start a new life away from the constant danger that has been associated with the name 'Harry Potter' for so long.
First, he needs to check the local laws regarding name change. Different places have different requirements. Usually, he will have to file a petition in the appropriate court. He should also provide valid reasons for the name change, which in this case could be related to privacy concerns due to the fanfic situation.
One reason could be to avoid using a common name that might make the character seem too generic. For instance, if your story is set in a world full of unique individuals, changing a 'John' or 'Jane' to something more distinct like 'Aria' or 'Zephyr' can make the character stand out.
One reason could be that he wants to avoid unwanted attention. In the fanfiction world, being overly intelligent might make him a target. Another reason might be that he is trying to fit in with a certain group that values other traits more. For example, if he's in a group that values physical strength over intelligence, he may hide his smarts to seem more like them.
One reason could be that he doesn't want his friends to worry. Harry often takes on a lot of responsibility and might see his sickness as a burden he doesn't want to place on others. Another reason could be related to his enemies. He might fear that if Voldemort or his followers find out he's sick, they'll see it as a weakness and target him more aggressively.
One reason could be for a fresh start. Just like in real life, if a character has a bad reputation or a past they want to leave behind, a new name can symbolize a new beginning. For example, a former criminal character in a story might change their name to escape their old identity. Another reason is for self - discovery. A character might change their name to better reflect who they feel they are inside. If they've gone through a major transformation, a new name can be part of that change.
It could potentially fall into the mystery genre if the 'hide' aspect involves some sort of mystery, like Harry Styles hiding something or being hidden. For example, it could be about a hidden identity or a secret he's keeping.
One reason could be fear. Maybe Harry discovers something about Dumbledore in the fanfiction that makes him scared, like a hidden agenda. Another reason might be to protect Dumbledore. Harry could think that by hiding from him, he is keeping Dumbledore away from some sort of danger that is related to Harry himself. Also, it could be due to a misunderstanding. Harry might misinterpret something Dumbledore does or says, and as a result, decides to hide from him.