Obviously, Harry Potter himself could be a main character. He could be drawn into the casino world either by curiosity or because he suspects some dark magic at play. Hermione Granger would also be a great main character. Her intelligence would help in understanding the complex magical rules within the casino.
Neville Longbottom could be an unexpected but interesting main character in a Harry Potter casino fanfiction. He has grown into a brave and capable wizard, and his presence in the casino could be due to a quest to find a rare plant that is rumored to be held there for some magical gambling purposes. Luna Lovegood could also be a main character, with her unique perspective on magic and the casino's strange happenings.
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 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 be there. She would be eager to study the different magics and books in Tamriel. Her intelligence would help Harry navigate the new world.
Obviously, Harry Potter himself could be the main character. He has the skills and the popularity from the original series. Ron Weasley could also be a main character, maybe as Harry's trainer or his corner man in the boxing matches. Hermione might be involved as well, using her intelligence to strategize for Harry's boxing career.
Another possibility is that the main character is the wizard who runs the pizzeria. He could be an old friend of Dumbledore's. And he hires some Hogwarts students to help him out. Fred and George Weasley might be interested in working there to try out some of their pranks on the customers, which would make for an interesting story.
Obviously, Harry Potter would be one of the main characters. Naruto Uzumaki would also be a key figure as he is the central character in Konoha. Hermione Granger could also be there, using her intelligence to figure out the new world she's in. And Sasuke Uchiha might play a role, perhaps being initially skeptical of Harry but later becoming his ally.
Hermione Granger could be a main character. Given her intelligence and knowledge of both the wizarding and Muggle worlds, she would be a great diplomat. She could use her skills to bridge the gap between different magical communities and even between wizards and Muggles in diplomatic matters.
A Hogwarts professor who has knowledge of both the wizarding world and some dark secrets related to other dimensions. This professor could play a key role in dealing with the Arrancar, whether it's trying to communicate with it or stop it from causing harm.
Draco Malfoy could be a main character in a wedding fanfiction. He could be marrying a witch who helps him redeem himself after the events at Hogwarts. Their wedding could be a sign of his new start in life. It might be held in a more secluded area of the Malfoy Manor, renovated to be less dark and foreboding, with a mix of old pure - blood traditions and new, more inclusive wizarding practices.