on Jane Friedman site:
As Christopher Vogler and other wise authors have observed, villains are the heroes of their own stories. Villains and antagonists have their own goals, needs, and desires to fulfill. They feel justified that the path they pursue is the right and righteous one. From their point of view, the so-called “hero” of a story is their opponent or enemy.
The Writer’s Journey: Mythic Structure for Writers by Christopher Vogler is the classic textbook for screenwriters and novelists that explains the Hero’s Journey. Since villains usually consider themselves heroes, they can also go through the same stages heroes do, with some important variations to be discussed a little later.
Here are the 12 stages the hero goes through:
Chris The Story Reading Ape's Blog 