In 'Dark Lady Fem Harry Potter Fanfiction', the central figure is Fem Harry as the Dark Lady. Hermione is frequently present. She could be trying to bring Fem Harry back to the light side or be in a power struggle with her. Ron is there too, sometimes as a loyal friend to Fem Harry, other times as someone who is wary of her new dark persona. Additionally, characters like Draco Malfoy often play a part, perhaps as a rival or an unexpected ally to the Dark Lady Fem Harry. The Hogwarts professors are also important, as they try to deal with the situation of having a Dark Lady in their midst.
Typically, the main character in 'Dark Lady Fem Harry Potter Fanfiction' is Fem Harry in the role of the Dark Lady. She is at the center of the story's action and development. Hermione is almost always a key character. Her intelligence and friendship with Fem Harry can be a major factor. Ron may be involved, his character often serving to contrast with Fem Harry's new dark identity. Voldemort or his followers might also be important in some stories, as Fem Harry, as the Dark Lady, could have a complex relationship with the forces of dark magic. And the Hogwarts faculty, such as McGonagall and Flitwick, are there to uphold the school's values and deal with the Dark Lady situation.