One reason could be a prophecy. In the wizarding world, prophecies often drive events. Maybe there's a new prophecy that says Harry must be at Hogwarts at a certain time for some great event to occur. So, the magical community, in an effort to fulfill the prophecy, forces Harry to go. It's like they are trying to shape the future according to the words of the prophecy.
One common theme is self - discovery. Even though Harry is forced to go, he still finds out more about himself and his powers at Hogwarts. Another theme is the idea of fate versus free will. He's forced, but he still has choices to make once he's there. For example, he can choose which friends to make or which classes to focus on.
One possible plotline could be that Harry initially resists going to Hogwarts because he's afraid of leaving behind his only connection to his normal life, like his aunt and uncle's house which, despite being horrible, is still the only home he's known. Another could be that some dark force is trying to prevent him from going to Hogwarts, but he's being forced by Dumbledore or some other powerful figure who knows it's crucial for his safety and development. For example, Voldemort could be using some magic to make Harry not want to go, in an attempt to keep him from learning magic and becoming a threat.
One popular 'Harry Forced to Go to Hogwarts' fanfic might be one where Harry's relatives are threatened by some magical force if they don't let him go. In this kind of story, it could add an extra layer of drama. Maybe there's a magical contract that was made before Harry was left with the Dursleys, and if they break it by not allowing him to Hogwarts, there will be dire consequences for them. It makes for an exciting read as we see Harry's journey start in a different way than in the original books.
Well, muggles going to Hogwarts in fanfic could lead to interesting scenarios. They might face discrimination from some pure - blood students who look down on non - magical folk. However, there could also be those who befriend them and help them navigate the magical world. The teachers would have a tough time too, having to teach magic to people with no prior knowledge of it, like starting from scratch with basic spells and magical theory.
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.
The fight against Voldemort would be very different. Since Hogwarts is a key place in the battle against the Dark Lord, if Harry isn't there, the defenses of Hogwarts might not be set up in the same way. Also, he won't be trained by the professors, so his magical skills won't develop as they did in the original story. Without Harry at Hogwarts, the balance of power between good and evil in the wizarding world could shift in a very unexpected way.
One possible reason could be fear. Maybe he's heard some scary rumors about Hogwarts, like the Forbidden Forest being full of dangerous creatures. Another reason might be that he doesn't want to leave his normal life behind. He has friends in the Muggle world and he might be reluctant to give that up for a world full of magic that he doesn't fully understand yet.
The plot might develop with Harry exploring the non - Hogwarts magical world. He could meet new characters who introduce him to different magical cultures and spells.
In the fanfiction world, Harry might be the heir to Hogwarts if there was some sort of magical pact made generations ago. For example, perhaps one of his ancestors had a special role in the creation or protection of Hogwarts, and this role was passed down through the family. It could also be that his unique magical abilities, like his ability to resist Voldemort's attacks from a young age, are signs of a deeper connection to Hogwarts itself. This connection could be what designates him as the heir in the fanfiction's plot.