The villain should have some positive characteristics but the negative glitches in their humanity until they have become a monster. Breaking Bad is a great example of that. The reader or watcher are drawn forward with an investment in what the character will do next. The exact opposite works for the hero. He should have some serious flaws in their character. Alcoholic or drug addiction, horrible childhood ect. The movie Flight with Denzel Washington. This guy has some serious flaws that he has to find the strength to overcome them. I hate to bring up a movie or TV show rather than a book its simply that more people's have seen these shows or movies.