One of the main themes is the idea of identity. The characters in the novel struggle with how they are perceived and how they truly are. For example, Coleman Silk has a complex identity that he tries to hide. Another theme is the power of secrets. The secrets the characters hold have a great impact on their lives and relationships. Racism is also a theme, as Coleman's attempt to pass as white has implications related to race in society.
Well, Coleman Silk is key. He's a man with a hidden past and a lot of inner turmoil. Faunia Farley, she's an interesting character who has her own set of issues and her relationship with Coleman is both passionate and complicated. Then there's Delphine Roux. She's involved in the events at the college that start to unravel Coleman's life. And of course, Nathan Zuckerman who helps us understand the whole story through his perspective.
One popular type might be a Stain crossover with other well - known anime characters. For example, a crossover with All Might could explore an interesting dynamic where their opposing views on heroism clash. Another could be a Stain crossover with Deku, perhaps showing how Deku's ideology might be challenged or changed by interacting with Stain.
One common theme is the clash of ideals. Stain has his extreme views on heroes, while Deku is the epitome of the traditional hero concept. Another theme is redemption. Sometimes Stain is shown on a path of redemption through his interactions with Deku.