Hermione would probably be involved. She's always by Harry's side, and she might be researching ways to help Harry tame the basilisk. Maybe she finds some useful spells or information in the library that gives Harry an edge.
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.
Well, it could be that Harry uses his Parseltongue ability to communicate with the basilisk. Maybe he convinces it that he means no harm and that they can co - exist peacefully in Hogwarts. He might offer it some sort of deal, like protecting it from those who would want to kill it just because it's a basilisk.
Hermione could be involved. She might suspect Daphne of having ulterior motives regarding Harry and try to warn him, which could play into the betrayal storyline in some way, either as a catalyst or as someone who helps Harry deal with the betrayal later.
In many fanfictions, Severus Snape could be involved. He has a deep knowledge of dark magic, so he might be either trying to prevent the basilisk ritual from being misused or he could be lured by the power it offers. Dumbledore is also a likely character. He would be the one to guide the students or other characters in dealing with the implications of the basilisk ritual. And of course, Tom Riddle (Voldemort) could be a key figure if the ritual has something to do with his rise to power or his plans for the wizarding world.
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.
The Weasley twins could be part of it too. Suppose Harry yells in excitement or anger about a new prank idea that the twins have come up with that might be a bit too dangerous. They could either encourage his yelling or try to tone it down, depending on their mood. And Malfoy might overhear Harry's yell and use it as an opportunity to taunt him, adding more conflict to the fanfiction.
Obviously, Harry Potter himself is usually one of the main characters. He is often the one who has to face the basilisk in these fanfictions.
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.
Hermione Granger is often involved. She's Harry's best friend and is extremely intelligent. Her knowledge of spells and magic history can be crucial in helping Harry prove his innocence. She might research old laws or spells that can be used as evidence.
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.