Obviously, the Princess of Hell would be one of the main characters. She would bring her own set of characteristics, motives, and powers to the story. Harry Potter himself would also be a main character as the story is set in his world. He would be the one to either oppose or befriend the princess. Hermione and Ron would likely be involved as well, providing support to Harry and having their own reactions to the new and strange character from hell.
Another possible main character could be a wizard or witch who has some connection to the underworld. This character could act as a bridge between the Princess of Hell and the wizarding world. They might have some past experiences or knowledge that helps in dealing with the princess. Also, Voldemort or his followers could play a role. If the Princess of Hell has some sort of power that Voldemort desires, he could try to either capture or make an alliance with her, which would then draw Harry Potter into the conflict even more.
The headmaster or headmistress of Hogwarts at the time could be a main character too. They would have the responsibility of protecting the school and its students from any potential threat that the Princess of Hell might pose. They would use their wisdom and magical abilities to assess the situation. And there could be some other minor characters from hell who follow the princess and add more complexity to the interactions between the two worlds.
The plot might revolve around the 'Princess of Hell' trying to bring some sort of hellish influence into Hogwarts. For example, she could be on a mission to corrupt the students or steal some powerful magical artifacts from the school for her own dark purposes. However, Harry Potter and his friends discover her plans and try to stop her. They might face many challenges as her powers could be quite different from the usual dark wizards they've faced.
Harry Potter is the central figure in this fanfiction. However, we may also see characters from the hellish realm introduced. There could be powerful demons or other supernatural beings that interact with Harry. Maybe there are some original characters created just for this fanfiction who play important roles in Harry's journey as the king of hell, like a trusted advisor or a fierce enemy.
Obviously, Harry Potter is the main character. He is the one who is raised in Hell in this fanfiction.
Obviously, the 'Prince of Hell' himself (or itself). This character would be extremely powerful, with abilities that are far beyond what Harry has faced before. It could have control over dark magic in ways that Voldemort could only dream of.
Most likely, Harry Potter would be one of the main characters. Since it's based on the Harry Potter series, he would probably be central to the story, perhaps leading the fight against the evils of this 'hell' side.
Since I haven't read this particular fanfiction, it's hard to say exactly. But it's likely that the black princess is one of the main characters. There might also be some of the original Harry Potter characters like Harry, Hermione, or Ron who could interact with her.
Harry Potter himself is often a main character. Since he's the hero of the original series, in fanfictions related to 'Harry Potter Lord of Hell', he might be the one to take on the lords of Hell or get involved in the Hell - related plot. Hermione and Ron are also likely to be main characters as they are Harry's closest friends and would support him in any adventure, including one that involves Hell.
There could also be an original princess created just for the fanfiction. She could have unique magical abilities of her own, like the power to control the elements. In this case, she and Harry would have a lot to share in terms of magic, and their relationship could be based on exploring and comparing their different magical powers. This original princess could also come from a completely different type of kingdom, with its own set of magical creatures and lore.
The princess could be a descendant of an ancient wizarding family that once ruled a small kingdom. She might have been hidden away from the wizarding world for her own protection. Harry could discover her existence during his search for something related to the history of magic. Her being a princess would add an element of royalty and mystery to the story, and her connection to the old wizarding family could bring in some interesting plot twists.
It might be a character from a different fairy - tale world that has been magically transported into the Harry Potter universe. Let's say it's Snow White. She retains her beauty and kindness but is now in a world full of wizards and witches. Voldemort or one of his followers wants to use her for some evil purpose and Harry Potter has to save her. He would be quite confused at first but then rises to the occasion.