Anne Lamott in Bird by Bird writes about the importance of learning about your characters as you’re writing them:
Say this boy meets a girl….Things need to happen. Then need to get to know each other, even if just a little. They will talk to each other, and they will talk about each other to friend. Get all this down. After you’ve spent a while with them, they will start to sound more like themselves–because you are getting to really know them…
The better you now the characters, the more you’ll things from their point of view. You need to trust that you’ve got it in you to listen to people, watch them, and notice what they wear and how they move, to capture a sense of how they speak.
As you learn who your characters are, compassion for them will grow. There shouldn’t be just a single important character in your work for whom you have compassion. You need to feel it even for the villain–in fact, especially for the villain. Life is not like formula fiction. The villain has a heart, and the hero has great flaws. You’ve got to pay attention to what each character says, so you can know each of their hearts.
The books that stay with you are the books that have characters with many dimensions to their personalities. Yin and yang. Evil in the good. Good in the evil.
One of my favourite examples of this is Laoghaire MacKenzie in Diana Gabaldon’s Outlander series. In the first book, we hate her for being so jealous of Claire that she sets her up to be burnt as a witch. By the end of the series we sympathize with the bitterness that grew when she realised her adoration was unrequited. She loves Jamie, and since we as readers do too, we can relate to her pain at not ever being loved as she wanted to be by the man she has loved since childhood. She believed erroneously that they were star-crossed lovers.
What examples from your reading support this view? What author is a master at this strong character development?