There's also a possibility that it could be a character who was thought to be dead in the original series but was actually saved and has now returned as the 'darkslayer' with a vendetta against the remnants of the dark side.
It might also be a descendant of one of the well - known characters from the Harry Potter series. For example, a grandchild of Sirius Black who inherits his rebellious spirit and uses it to fight against the new dark forces as the 'darkslayer'.
Another interesting plot could be that the 'darkslayer' discovers a secret society within Hogwarts that is secretly training students in dark magic for some ulterior motive. And the 'darkslayer' has to expose this society while also dealing with the regular threats of the wizarding world.
It could be a new character, like an assassin from a far - off land who comes to Hogwarts under false pretenses. They have their own set of skills and motives that are different from the regular characters in the Harry Potter series.
It could be a young witch who is just starting to explore her magical abilities outside of Hogwarts. She takes on a babysitting job to earn some extra money and ends up having all sorts of magical adventures with the kids she babysits.
A Muggle - born wizard could be the main character. They are used to the Muggle concept of hairdressing but also want to incorporate their new - found magic into it. This character would be constantly trying to bridge the gap between the two worlds in their salon, creating a unique blend of Muggle and wizarding hairdressing styles.
In one fanfic, Gabrielle gets involved in an international wizarding competition that is not the Triwizard Tournament. This competition tests different magical abilities, and Gabrielle shows her courage and determination as she competes against some of the best young wizards from all over the world. It's a story of her growth and self - discovery.
Obviously, Harry Potter himself could be the main character. Given his adventurous nature, he would be a great fit to incorporate parkour into his already impressive list of skills. He could use parkour to explore new areas of Hogwarts or to escape from dangerous situations.
Perhaps Accelerator from the railgun universe could be the main character. He has his own set of abilities that would be very interesting to transplant into the Harry Potter world. He might initially be seen as a threat due to his powers but then end up using them to fight against a common enemy, like a new dark wizard or a powerful magical creature that has gone rogue.
Neville could also be a main character. He's often underestimated, but if he found the Harry Potter headphones, it could be his chance to shine. He could use the power of the headphones, whatever it may be, to stand up to bullies or to help protect Hogwarts. Maybe the headphones give him the confidence he needs to become a hero in his own right.
It could be Harry Potter himself, as the title still has 'Harry Potter' in it. So, the story might revolve around him in this new vampire - infused plot.
It could be a long - lost relative of Harry Potter. Maybe a cousin who was hidden away for some reason and now discovers their magical heritage. They could have a different personality from Harry, like being more shy and studious but still having a great sense of justice.