Perhaps he would go to Diagon Alley. There are many wizards there, and he could hide among the crowds. He could also try to find some help from the shop owners, who might be sympathetic to his situation. He could use the resources there to start a new life away from his parents for a while.
He might run away to the Forbidden Forest. Although it's dangerous, he is brave and has some knowledge of the forest. He could find a hidden place deep in the forest to stay. He might also encounter some magical creatures that could help him or at least keep him company while he figures out what to do next.
He could go to Hogwarts early. Since he has some connection to the school already through his parents, he might think that the school could be a safe haven. There are also his friends' families there, like the Weasleys, who might take him in.
One possible reason could be that he discovers a dark secret about his family. Maybe he finds out that his parents were involved in something dangerous or unethical in the wizarding world, and he can't bear to be associated with it, so he runs away.
He could go to the Forbidden Forest. It's a large and mysterious place where he could hide. There are many hiding spots and magical creatures that could either protect him or at least keep his presence a secret.
He could go to the mountains. There are so many hidden caves and areas in the mountains that he could explore. It would be a great place for him to hide and be alone with his thoughts. Plus, there might be some powerful Pokémon that live there that he could interact with.
He might go to his mother's place. It's a place where he has always felt safe and loved. His mother has always been his anchor, and even though it might be a risky move as monsters could track him there, it could be his first instinct. Another option could be to go to a big city like New York. There are so many people and places to hide. He could blend in with the crowds and use the chaos of the city to stay unnoticed. He could also find refuge in an abandoned building or a place that has some sort of magical protection that he discovers by accident.
In some fanfics, a time - traveling accident might cause Harry to be taken away from his parents. For example, if a wizard from the future accidentally creates a rift in time while trying to save Harry from Voldemort in a different way. They end up pulling Harry into the future, separating him from his parents in the past. This could lead to a story where Harry has to find a way to get back to his own time and reunite with his family, all while dealing with the strange future world he's landed in.
Hermione could be one of the main characters. She might be the one who tries to find Harry and bring him back. She would use her intelligence and knowledge of magic to track him down, all while worrying about his safety.
He could stumble upon a hidden wizarding community that has been cut off from the rest of the world for centuries. There, he might learn new magic spells and techniques that are unknown to the outside wizarding world.
If Harry was taken away from his parents in a fanfic, he might be more distrustful. Without the love and security of his parents in his early years, he could have a harder time forming close relationships. He may also be more self - reliant, having to figure out things on his own from a young age.
Well, he could meet new friends or allies who help him grow stronger. For instance, he might encounter a group of outcasts who understand his situation and teach him new skills or ways of thinking.
He could run to the Forbidden Forest. It's a place full of mystery and danger, but also a good hiding place as it's vast and not many people would expect him to be there. He might find some solace among the magical creatures there.