Obviously, Harry Potter is a main character. His friends like Hermione Granger and Ron Weasley are also often involved. They usually accompany Harry in his adventures around Hogwarts.
Sometimes, other characters like Neville Longbottom become more prominent. Since they are all staying at Hogwarts, Neville might show his skills in Herbology in a new and exciting way, perhaps finding a magical plant that has been lost for centuries. And of course, some of the teachers like Dumbledore or McGonagall may also play important roles in these fanfictions.
Obviously, Harry Potter himself is the central character. Then there are the Hogwarts teachers like Dumbledore. Dumbledore would likely play a huge role in Harry's upbringing, guiding him not only in magic but also in moral and ethical matters. Hagrid would also be an important figure, perhaps teaching Harry about magical creatures from a very young age.
Another character that could be involved is Nico di Angelo. Since he has some experience with the Underworld and Tartarus, he might try to find a way to communicate with Percy or even attempt a rescue mission. His powers and knowledge would play an important role in any interaction with Percy in Tartarus.
Harry Potter himself is often involved. He might be the one to encounter the first signs of inflation, whether it's a magically inflating potion or an enchanted object. His friends, like Ron and Hermione, are also likely to be part of the story, helping him figure out what's going on.
Ron Weasley could also be a key figure. He might be Harry's loyal friend as always, standing by his side during all the changes that Harry is bringing about in the wizarding world as a god. And there could be new characters introduced as well, perhaps other gods or magical beings that interact with Harry in this new fanfiction realm.
In some cases, Albus Dumbledore could play an important role. His wisdom and power in the wizarding world would make him a key figure in any situation where the two different universes collide. He might be the one to first discover Alexstrasza's presence and figure out how to make use of her abilities in the fight against the dark forces in the Harry Potter world.
Obviously, Harry Potter himself is always a main character. He is the one most directly associated with the concept of death in the original series, what with his parents' death and his multiple near - death experiences.
Ron Weasley could be another main character. He might be initially skeptical about the piano's magic but then be amazed when he sees the extraordinary things it can do. Maybe he accidentally discovers a new function of the piano while fooling around with it in the Gryffindor common room.
Harry Potter himself could be one of the main characters in such fanfiction. Maybe he gets an automail limb after a particularly dangerous encounter with Voldemort. Hermione might also be involved, using her vast knowledge to help understand and improve the automail technology within the wizarding context.
Well, of course, Harry Potter himself is often the central figure. He's usually the one who discovers the amulet or is tasked with dealing with its powers or secrets. Hermione Granger also frequently appears, using her vast knowledge to help Harry understand the amulet.
Harry Potter himself is often involved. He might be the one to discover a mysterious egg or be tasked with protecting it. Hermione Granger could also be a main character, using her vast knowledge to figure out the nature of the eggs. Ron Weasley might be there too, providing some comical relief while also helping with the situation.