Maybe for the sake of novelty. People might be tired of the traditional good - vs - evil story in the Harry Potter world and want to explore a completely different take on the character. It could also be an attempt to show how power can corrupt, even someone like Harry who was initially on the side of good.
Maybe the writer wants to be different and create a shock factor. By making Harry a dark wizard, it goes against the common perception and grabs attention.
One reason could be that Harry has had enough of the wizard world's troubles. He might want a normal life away from magic. After all he's been through, like fighting Voldemort and losing many friends, he may just be tired of the whole wizarding business.
Some people might write it for shock value. They want to create something that is so out - of - the - box and unexpected that it grabs people's attention. It could also be a way for them to explore very extreme and dark 'what - if' scenarios in the Harry Potter universe, even if it goes against the original story's essence.
Some people might write it for shock value. They want to create something that is completely unexpected and out - of - the - box, even if it's inappropriate. It could also be a very misinterpreted exploration of the characters' relationships, where the writer has a warped view of the family dynamics in the 'Harry Potter' world.
One reason could be a powerful dark magic spell cast upon him by a new villain in the fanfiction world. This spell might be designed to make him disappear from the wizarding world entirely.
One possible reason could be that a powerful dark magic spell has been cast on him. Maybe a new dark wizard or witch, created specifically for the fanfiction, has found a way to make him vanish to cause chaos in the wizarding world. Another reason might be that Harry has chosen to disappear himself. Tired of the constant attention and danger, he decides to go into hiding, perhaps using some long - forgotten magic or a powerful magical object to conceal his presence.
Some might write it for shock value. They want to create something that stands out and gets a strong reaction from readers. It could also be a way to explore very extreme and unconventional character relationships, pushing the boundaries of what's possible in the Harry Potter universe.
Maybe he's curious about different interpretations of his own story. In fanfictions, his character might be in new and exciting adventures that the original books didn't cover.
One possible reason could be that he has been through so much in his original adventures that he's just tired. He might feel like he's constantly being put in new, often contrived, situations in the fanfiction and he simply wants to step away from all the chaos and drama.
Well, it could be a result of a dark spell cast on him by a Death Eater. Maybe they found a new and insidious way to harm him without leaving an obvious trace.