Most likely, Harry Potter, Hermione Granger, and Ron Weasley would be main characters. Since it's a fanfiction related to the Harry Potter series, they are the central figures in the original story and would probably play important roles in any fan - created plot where they are 'busted'.
It's also possible that new or minor characters from the original series could be the main focus in a 'busted' scenario. For example, Neville Longbottom could be the main character if the fanfiction is about him getting 'busted' for standing up to bullies in a way that violates the school rules but is still heroic.
It could also be a fanfiction that focuses on the darker side of the wizarding world and how the characters are 'busted' by the wrong side. For example, if the Death Eaters or some other dark forces manage to expose the Order of the Phoenix's plans and the members are 'busted'. It all depends on the creativity of the fanfiction writer.
In addition to the ones mentioned, Dumbledore could be a main character in some fanfictions. He knew Flamel, so he could play an important role in stories about Flamel. Voldemort could also be a main character as he was after the Philosopher's Stone, and his actions could be intertwined with Flamel's story. There could also be original characters created by the fanfiction authors who interact with Flamel and the other known characters.
It could be that Dumbledore plays a more prominent role in this fanfiction. Since it's about 'the truth', perhaps Dumbledore has some secrets that are finally revealed, and he becomes a central figure in guiding Harry towards understanding. Additionally, some minor characters from the original series might be elevated to main characters if they hold key pieces of the truth.
I'm not sure specifically as it depends on the particular fanfiction. But it could include Harry Potter himself, perhaps having a special connection to Ancalagon. There might also be new characters created specifically for this fanfiction that are key to the Ancalagon - related storylines.
It's hard to say for sure without reading it, but it's likely that Harry Potter himself would be one of the main characters. He could be at the center of the story, dealing with the brimstone - related events. Hermione and Ron might also be involved, using their skills and knowledge to help Harry figure out what's going on with the brimstone mystery.
The main characters are usually James Potter, Sirius Black, Remus Lupin, and Peter Pettigrew. They are known as the Marauders. James is often depicted as a confident and talented wizard. Sirius is the rebellious one, with a bit of a wild side. Remus is the more reserved and intellectual one, due to his condition as a werewolf. And Peter is the tag - along, though his character can be quite complex in different fanfictions.
Hermione Granger might also be a main character. Given her intelligence and thirst for knowledge, she would probably be involved in researching about Phobos and its implications in the magical world. She could be the one to figure out how to use or counter any threats related to Phobos.
The demiwizard themselves would likely be a main character. They are at the center of the story given the title. There could also be some traditional 'Harry Potter' characters like Harry, Hermione, or Ron who interact with the demiwizard and play important roles in their journey.
Well, Harry Potter would likely still be one of the main characters. He might be the one to discover the seals and their significance in the magical world. Hermione would also be important as she would use her vast knowledge to research about the seals. Ron could be there for moral support and also to join in on the adventures related to the seals.
Well, obviously Harry Potter is one of the main characters. He's the boy who lived, and in this fanfiction, his actions and decisions are likely to be central to the story. And then there's Greera. She's a character specific to this fanfiction. Her character traits, like her personality, her magical abilities if she has any, and her backstory would play a major role in the story as well.