What is villain arc?

A villain arc is a type of character arc where the antagonist or villain of a story undergoes a significant transformation throughout the narrative. Rather than remaining a one-dimensional enemy or obstacle for the protagonist, the villain arc allows for a more complex and engaging portrayal of the antagonist. This transformation may involve a shift in motivations, perspective, or behavior, and can lead to the villain becoming a more sympathetic or multi-faceted character. The villain arc can add depth and nuance to the story, and can challenge readers' preconceptions about good and evil. Examples of stories with notable villain arcs include "Breaking Bad," "Wicked," and "The Dark Knight."