Taking a Heroine to the Next Level

I feel like the villain that I'm primarily writing has more of a darker, more of a larger cast. There's several villains. We could go into more, but I feel like I'm going to say spoilers. It can be really interesting to explore the layers of human nature and psychology because your character is a result of what's happened to them. Even just those few basic questions will take your villain to a way better level than most cliché villains. And even if you just have to write backstory for yourself, like it doesn't even need to go in the book necessarily. It probably should be referenced or at least pointed to, alluded to.