One reason could be that it doesn't stay true to the original lore. For example, if the fanfiction changes the fundamental rules of magic in Hogwarts that were established in the original series. Another reason might be that the characters' personalities are distorted. Harry Potter is known for his courage and self - sacrifice, and if the fanfiction turns him into a cowardly or self - centered character, it could be rejected.
Perhaps in the fanfiction, the idea of Harry rejecting magic is a form of rebellion. He might have seen the negative impacts of magic on the wizarding world, such as the power struggles and dark magic. So, he decides to take a stand against it. Another possibility is that the writer wants to show how much of Harry's identity is tied to magic and by rejecting it, he goes through a major transformation.
One possible reason could be that he was under the influence of a powerful dark magic or a curse that made him lose control. Another reason might be that he was tricked into believing Hogwarts was a threat to the wizarding world in some extreme way. Maybe a powerful enemy manipulated him to think that destroying Hogwarts was the only way to save everyone.
One possible reason could be differences in their social status. In some fanfiction settings, Daphne might come from a pure - blood family with high - society expectations, and Harry, being an orphan with a somewhat 'outsider' status in the wizarding world, may not meet those expectations. Another reason could be conflicting personalities. Maybe Daphne is a very reserved and traditional person, while Harry is more impulsive and adventurous, which could lead to her rejection.
One possible reason could be that in the original 'Harry Potter' lore, Draco and Harry are from rival houses and have a history of animosity. So in fanfiction, Draco might reject Harry based on this pre - existing enmity. For example, Draco's pure - blood supremacist views might clash with Harry's more inclusive attitude.
He might leave Hogwarts in fanfic due to a sense of disillusionment. Maybe he discovers some dark secrets about the school or the wizarding world in general that make him question his place there. It could be something related to the way the school is run or a conspiracy among the teachers that he stumbles upon.
In this fanfiction, it could be that Harry has a falling - out with Dumbledore or other important figures at Hogwarts. This makes him feel unwelcome or betrayed, leading him to choose not to go to Hogwarts and seek another path in the magical world.
In some fanfictions, Harry might be expelled for being wrongly accused of using dark magic. Maybe someone framed him by planting dark magic items in his dorm. Another reason could be that he continuously breaks school rules in a way that the school can't tolerate, like sneaking into the Forbidden Forest too many times without permission.
Perhaps he runs away because he feels misunderstood. In the fanfiction, the other students or even some of the teachers might wrongly accuse him of something. He could be tired of constantly having to defend himself. Like if he was wrongly blamed for a serious incident at Hogwarts, and no one seemed to believe his innocence, he might just leave in frustration.
One possible reason could be that he felt he had learned enough magic to face his enemies on his own. He might have thought that the traditional Hogwarts education was too slow or not relevant to his specific needs, like dealing with Voldemort. Another reason could be some sort of conflict with the Hogwarts faculty. Maybe he didn't agree with their methods or decisions and decided he was better off without their rules.
In some fanfictions, there could be a change in the Hogwarts admission policy. Maybe they found some supposed flaw in Harry's magical abilities or his background that led to his admission being revoked at the last minute, so he didn't arrive at Hogwarts. Also, it's possible that some other powerful magic was at work. A powerful wizard or witch could have cast a spell on Harry that made him forget about Hogwarts or made it so that he couldn't physically reach the school.