Dumbledore's portrait could play a significant role as well. His wisdom could be guiding the new generation through difficult times. And don't forget about the teachers at Hogwarts. Professors McGonagall, Snape (through memories or other means), and new professors could all be main characters in different ways. They could be the ones teaching the students the skills they need to face whatever threats come their way in the new stories.
Well, it's likely that Harry Potter himself could still be a main character, perhaps as a mentor to the new generation. His children might also be main characters, as they carry on the Potter legacy at Hogwarts.
Hermione and Ron could be main characters too. They've been through so much with Harry, and their knowledge and skills would be very useful in new adventures. Also, there are other characters like Neville, who has grown so much, and he could play a major role in the new stories. There might even be new characters that are introduced and become central to the plot.
Ginny Weasley could also be a main character, especially if the story is set in a time when she is married to Harry. Their relationship and family life might be an important part of the story. And, of course, Albus Dumbledore's influence might still be felt in the story, even if he's not physically present, as his wisdom and the secrets he left behind could play a role, so in a sense, he could be considered a main 'character' in terms of his impact on the events.
Most likely Harry Potter himself. But there could also be other familiar characters like Hermione, Ron, and Dumbledore.
Perhaps some new students from different parts of the wizarding world could be main characters. For example, a student from a far - off magical school who comes to Hogwarts on an exchange program. They could bring new perspectives and magic styles to Hogwarts. And of course, Ginny and Harry's daughter Lily could also play a major role in the story.
It's hard to say without reading it. It could be the original characters like Harry, Hermione, and Ron if it's a continuation of their story. Or it might focus on new characters created by the fanfic author.
Most likely, Harry Potter will still be a main character, but perhaps with a different personality or set of skills. Hermione Granger and Ron Weasley may also be main characters, but they could be given new story arcs. There might also be new characters introduced that play important roles in the fanfiction.
Harry Potter himself is sure to be one of the main characters. He's the central figure in the whole series. Hermione Granger and Ron Weasley are also likely to be main characters as they are always by Harry's side in most of the adventures.
Harry Potter himself is a main character. His experiences during Christmas at Hogwarts are often central to the stories.
It's likely that Harry Potter himself would still be one of the main characters. Hermione and Ron would probably also play important roles. However, there could be new characters introduced as well that are central to the new order concept.
Obviously, the marauders themselves - James Potter, Sirius Black, Remus Lupin and Peter Pettigrew. They would be central to the story as they are the ones the fanfiction is named after.