Clemence and Audiard seem to be the central figures, perhaps the ones driving the detective work. Rae Lil Black is also a main character, whose role is probably crucial in the plot. Maybe she is the one who has brought the mystery to their attention, or she could be the target of some sort of intrigue that Clemence and Audiard need to figure out.
In this detective story, Clemence and Audiard are the main protagonists as they are the ones who are supposed to solve the mystery. Rae Lil Black is another important character. She could be a victim, a suspect, or a witness. Her actions and her story are what Clemence and Audiard are going to be investigating. There could be other characters as well, but these three are likely to be the most prominent in the story.