Obviously, the illithid would be a main character. It could be a mysterious and powerful being that Harry encounters. Also, Hermione and Ron might still be important characters. They could be either suspicious of the illithid or try to help Harry understand it better. Dumbledore might also play a role, perhaps guiding Harry in his interactions with this strange new creature.
The illithid, of course. But there could also be other magical creatures that are associated with the illithid in some way. For example, there might be a smaller, more docile version of the illithid that acts as a messenger or guide. Neville could also become more involved in this story. Maybe he discovers something about the illithid that helps Harry in his journey. And then there's Snape. His knowledge of the dark arts might be crucial in dealing with the potential threats that the illithid could bring.
Well, Hagrid would be a great addition. He could bring in some friendly magical creatures for the preschoolers to see, like baby owls or small unicorns. The kids would be thrilled to meet them.
Hermione would definitely be involved. She's always been by Harry's side, and in this kind of fanfic, she would likely be helping Harry in his struggle, using her intelligence to figure out solutions to the problems he faces. Ron would also be there, providing his loyalty and courage in the fight. Dumbledore might make an appearance too, perhaps as a guiding spirit or in flashbacks, offering his wisdom to Harry as he battles towards salvation.
Hermione would likely be a main character. She might be the one who tries to guide Harry in using his new powers wisely. Ron could also be there, perhaps being a bit in awe of Harry's new status but still being his loyal friend. Dumbledore might also play a role, even if it's from beyond the grave. His wisdom could be a guiding force for Harry as he navigates his god - like existence.
The Weasley family in general would be involved. Ginny, for instance, would be heartbroken seeing Harry on Voldemort's side. The family's loyalty to Harry would be put to the test, and they would be among the main characters as they try to either bring Harry back or fight against him if he goes too far with Voldemort.
Maybe Neville could be involved too. He has shown great courage in the original series. In this fanfic, he could be the one who has some prior knowledge about the dragon due to his family's history in the wizarding world. His knowledge could be crucial in helping Harry enter the dragon's territory and deal with whatever lies within.
Hermione would surely be one. She's smart and would be great at helping with the academic side of building a school, like creating the curriculum.
Harry Potter himself could be a main character. He has a history of standing up against injustice, so it's likely he'd be involved in a revolt. Hermione would also be a key figure. Her intelligence and knowledge of the wizarding world's laws would be invaluable in planning and leading a revolt. Ron, with his loyalty and courage, would be right there with them.
Harry Potter would probably be one of the main characters. He's the central figure in the original series, so it's likely he'd be involved in this fanfic in some capacity, perhaps as the hitman or someone related to the hitman - style plot.
Most likely, Harry Potter, Hermione Granger, and Ron Weasley will still be the main characters. After all, they are the central figures in the original series. But there could also be new characters introduced who are either part of their wealthy new circle or those who are affected by their millionaire status.
Obviously, Harry Potter himself would be one of the main characters. He's the hero of the original series and his story would likely continue in this fanfic.