Perhaps a new student from a far - off land could be the main character. This student could bring new magical traditions and knowledge to Hogwarts, and have to deal with the cultural differences while also getting involved in some big adventure, like unravelling a mystery that threatens the entire wizarding community.
Another possibility is Teddy Lupin. He has a unique background being part werewolf and having been raised by the Weasleys. He could be the main character in a story where he struggles with his identity while also trying to protect the wizarding world from a new and unexpected danger, like a new form of dark magic that targets half - bloods and werewolves.
It might be a new transfer student from a far - off magical school. This student brings with them the knowledge or potential to be the new Merlin figure. They could have a different approach to magic compared to what's taught at Hogwarts, which makes them stand out as a possible Merlin - like character.
Maybe it's a character who has been in the background in the original books but now gets their chance to shine. Like a house - elf who decides to break free from their servitude and start a new life. They could discover their own magical powers that were suppressed all this time and use them to create a whole new existence for themselves in the wizarding community.
A former Death Eater who has had a change of heart could be the main character. They are now trying to make amends and start a new life. Their past experiences would make them a complex and interesting character as they struggle to fit into the new, post - Voldemort wizarding society.
It could be a new student at Hogwarts. This student might come from a non - magical family but has a strong connection to magic that they didn't know about before. Their journey at Hogwarts would be their new beginning at life in the wizarding world.
Maybe a new character, a Muggle - born who discovers they have a special ability that no one else has. This character would then be thrust into the wizarding world and have to navigate through Hogwarts while also being the key to solving a big mystery in the new game story. They would interact with the old characters' descendants and form new friendships and rivalries.
It could be a long - lost relative of Voldemort, carrying on his dark legacy.
How about Neville Longbottom? He could be the main character in a fanfiction set in the Chamber. Neville, who has always been underestimated, could show his true courage and strength. He might discover a hidden ability that helps him face the challenges in the Chamber, perhaps something related to his connection with plants, which could play a crucial role in defeating the Basilisk or whatever new threat is in the Chamber.
An old ex - Auror who now lives near Hogwarts. He could have a past connection to Voldemort and some knowledge about the Dark Arts used in the Triwizard Tournament. He becomes an unofficial mentor to Harry, teaching him some unique spells and strategies that are not part of the regular Hogwarts curriculum. This character could bring a new perspective and a bit of wisdom to the story.
A young Auror who is assigned to help guard Azkaban but has a secret sympathy for the prisoners. This character could add a new dynamic to the story as they struggle between their duty and their conscience.
It could be a rogue Death Eater who escaped punishment and has been biding his time. He might have a new, more insidious plan to bring back the dark ways of Voldemort.