In addition to the founders and the students, some of the professors at Hogwarts could be main characters. Professors who have a deep understanding of Hogwarts' history might be the ones to communicate with the founders on an equal level. They could help bridge the gap between the ancient magic of the founders and the modern ways of magic at Hogwarts. For example, Professor McGonagall, with her long tenure at the school and her knowledge of Transfiguration, could play an important role in interacting with the founders and guiding the students during this extraordinary event.
Obviously, the four founders - Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw, and Salazar Slytherin would be main characters as they are the ones returning.
The main characters could also include some of the current students at Hogwarts. They might be the ones who first encounter the founders or are chosen by them to help in their mission. For instance, a brave Gryffindor student who is eager to learn from Godric Gryffindor himself. And a clever Ravenclaw student who catches Rowena Ravenclaw's attention with their intelligence. There could also be a Slytherin student who has to grapple with the return of Salazar Slytherin and his ideals. And a Hufflepuff student who embodies the kindness and loyalty that Helga Hufflepuff values.
Well, it could be about the founders coming back to Hogwarts to fix some long - standing issues. Maybe they return to deal with the dark magic that has seeped into the school over the centuries.
Obviously, the founders themselves. Salazar Slytherin would be fascinating as he could show a different side of his personality, not just the one associated with the dark wizards who came from his house. Godric Gryffindor would be full of bravado and heroic deeds, inspiring everyone around him.
In addition to the trio, there could be characters like Professor McGonagall. She would surely notice the changes in Harry and might try to guide him. Also, the ghosts of the founders themselves could be considered main characters in a sense. Since Harry is possessed by them, they would have a significant influence on the story, perhaps communicating with Harry or causing events to unfold around him.
Obviously, the main characters would be Merlin, Harry Potter, and probably the founders would be mentioned or play some role in the background. After all, Merlin is from their era.
One possible plot could be that the founders return during a time of great crisis at Hogwarts. Maybe a new dark force is emerging and their magic and wisdom are needed to combat it. They could help modernize some of the old Hogwarts traditions while also teaching the students the purest form of magic that was once known in their era.
Neville Longbottom is another possible heir. He has a strong connection to Gryffindor through his family's long - standing association with the house. His growth from a shy and clumsy boy to a brave and powerful wizard could be part of a story where he is the heir of the founders. His ability to stand up to the Death Eaters in the final battle shows his hidden strength, which could be related to the founders' magic.
There could also be new characters introduced in the fanfic. Maybe a young, talented wizard or witch who is just starting at Hogwarts and becomes involved in Harry's return journey. They could bring a fresh perspective and new abilities to the story. And of course, Dumbledore, even if he's not physically present all the time, his influence and legacy are likely to play a role, so he can be considered one of the important characters in a sense.
Often, the main characters would be the heirs themselves. There could be a character who is the heir of Gryffindor, perhaps a young student who has always shown great courage and a sense of justice. Another main character might be the heir of Slytherin, who at first seems a bit of an outcast because of the negative reputation of Slytherin but turns out to have a complex and important role.
Obviously, the four founders - Godric Gryffindor, Helga Hufflepuff, Rowena Ravenclaw and Salazar Slytherin are main characters as they are being reborn. They bring their unique personalities and magical abilities back to the story.
The apprentice is obviously one of the main characters. They are likely to be a young wizard or witch with great potential. Then there might be characters representing the different houses of Hogwarts, like a descendant of Gryffindor who is a mentor to the apprentice. There could also be a rival apprentice who has different ideas about the founders' magic.