Obviously, Harry Potter himself could be a main character. He would be the one to first encounter the Enderman and try to figure out what it is and whether it's a threat or not. Hermione Granger would also be a crucial character. With her vast knowledge of magic, she could try to research about the Enderman, its possible origins and how to communicate with it. Ron Weasley could provide some comical relief in the story, especially when he's initially scared of the Enderman but then tries to be brave. And of course, the Enderman itself could be considered a main character. It has its own motives, abilities and personality that would drive the story forward.
One possible plot could be that an Enderman accidentally gets teleported into the Harry Potter world. It could start by appearing in the Forbidden Forest, scaring some of the magical creatures there. Harry and his friends discover it while exploring. At first, they're cautious, thinking it's some new dark magic creation. But as they observe, they find that the Enderman is just lost and confused. The Enderman, with its unique abilities like teleportation and picking up blocks, could create some interesting situations. For example, it might accidentally teleport into Hogwarts and disrupt a class by picking up objects and moving them around. Eventually, the students and the Enderman could form an unlikely friendship and help each other. The Enderman could use its teleportation skills to help Harry and his friends in a dangerous situation, like escaping from Death Eaters.
Neville Longbottom could be a main character. He has always had the potential for great things and in a world without Harry, he would be likely to step into the spotlight. He has the courage and the connection to Hogwarts that could make him a central figure in the fight against evil.
Hermione could be there. She would be eager to study the different magics and books in Tamriel. Her intelligence would help Harry navigate the new world.
Hermione could be a main character. As a very intelligent witch, she might assist Harry in his teaching, like helping him prepare complex lessons or providing additional knowledge to the students. For example, when Harry is teaching about ancient spells, Hermione could offer insights from the books she has read.
Hermione could be one. She could come to Degrassi to help Harry. She'd be really good at handling the academic side of things there, like helping students with their studies. And also, she could use her magic knowledge to figure out any magical mysteries.
Hermione could also play a role. Given her intelligence and love for learning, she might take an interest in accounting to better manage the finances of the various causes she's involved in, like the Society for the Promotion of Elfish Welfare. So she could be a main character or at least a supporting one in this fanfiction.
Obviously, Harry Potter himself could be a main character. He could be the one who is initially reluctant to participate in a dance event but then discovers a new passion for it. Hermione could also be a main character as she might be the one researching the history and significance of different wizarding dances.
In addition to the main trio from the Harry Potter series, there could be some of the Hogwarts professors as main characters. For example, Professor Dumbledore might have some knowledge about the balverines that he imparts to Harry. And Hagrid, with his love for all kinds of strange creatures, could be involved in trying to tame or at least understand the balverines better.
Harry, Hermione and Ron could be the main characters, exploring the mysteries of the mansion. Or perhaps a new generation of wizards, like the children of the original trio. Neville Longbottom could also be a main character, using his knowledge of plants to uncover secrets in the mansion's garden.
Even Neville Longbottom's descendants could be interesting main characters. Maybe his grandson has a unique talent for herbology, like Neville did. He could use his skills to uncover a plot that involves poisoned plants in the Hogwarts gardens and throughout the wizarding world, and along the way, he becomes a hero in his own right.