Dumbledore could also play a significant role. He might initially be concerned about Harry's new attitude but later come to see the value in it, especially if it means saving the wizarding world from a greater threat. On the other hand, some of the Death Eaters could be main characters in the sense that they are the targets of Harry's ruthlessness, with their own motives and actions driving the story forward as Harry tries to take them down one by one.
There could be new characters introduced in this fanfiction. For instance, a powerful dark wizard who is an equal match for the ruthless Harry. This character could be the main antagonist, constantly challenging Harry and forcing him to use his ruthlessness to the fullest. Or perhaps a mysterious mentor figure who helps Harry hone his ruthless side, teaching him skills and knowledge that are not part of the traditional Hogwarts curriculum.
I don't know for sure as I haven't read it. But likely there's the ruthless king himself. There may also be his advisers, some of whom might be trying to temper his ruthlessness, while others might be enabling it. And there could be a love interest for the king, who might try to change him or be affected by his actions.
There could also be some side characters, perhaps a mentor figure who taught the protagonist how to use the ruthless sword. And maybe a love interest who is caught in the middle of the conflict between the protagonist and the antagonist.
The gods and goddesses also play important roles in these fanfictions. Zeus might be a figure of authority that Percy has to deal with, especially if Percy's new - found ruthlessness starts to disrupt the balance among the demigods. Athena could also be involved, perhaps guiding Annabeth on how to handle Percy's transformation.
The main characters are, of course, the female lead and the ruthless alpha king. There might also be secondary characters like the king's loyal followers or rivals within the pack.
The main character is Harry, given his immortality is the focus. Ron and Hermione are likely to be main characters too as they are integral to Harry's story. But it's also possible that descendants of other characters become important. For example, if Ginny and Harry had a relationship in the original story, their descendants could have a role. Additionally, there might be ancient magical beings that become part of the story due to Harry's immortality and his new connections to the deeper mysteries of the wizarding world.
Obviously, Harry is one of the main characters. His two triplet siblings are also central. Depending on the fanfiction, they could be named something unique, like James and Lily (not to be confused with Harry's parents). Then there are the usual Hogwarts characters like Hermione and Ron who interact with the triplets in different ways, sometimes being suspicious at first of the new addition to the group, and other times being quick to accept and help them.
The main characters are Harry and Hannah. Harry is typically depicted as the brave and resourceful hero we know from the books. Hannah can be a new addition to his world. She might be someone who has her own secrets and powers. For example, she could be a seer who can predict future events, and her visions play a crucial role in the story's plot as she and Harry try to prevent disasters or solve mysteries.
In most Harry Newts fanfiction, Harry and Newt are the central figures. Harry often represents the more combat - oriented side of the wizarding world, while Newt is the more research - and - conservation - minded. Their interactions can vary from being teacher - student like, where Newt teaches Harry about creatures, to being equal partners in some grand adventure.
Well, obviously Harry Potter is one of the main characters. He's the boy who lived, and in this fanfiction, he'll likely be involved in all kinds of adventures with the twins.
The main characters are Harry and Akeno. Harry is often based on the character from the 'Harry Potter' series, with his magical abilities and his brave and determined personality. Akeno, on the other hand, is from a different fictional context, usually having her own set of powers and a unique personality. In the fanfiction, their personalities and abilities are what drive the story forward as they interact with each other.