Best-selling author David Mitchell has populated books like Cloud Atlas with an array of characters who are neither purely good nor purely evil. That's because archetypes are "dull as ditchwater." Good writing and strong novels depend on narratives built upon nuanced characters. Shades of gray are interesting. The alternatives are not.
Mitchell's latest novel (published in October 2015) is called Slade House.
David Mitchell: My job is to perform an act of mimesis of the world, to recreate it in text. And if I view, as I do, the world as a place of many infinite shades of gray, then it’s my job to try to do the same within the level of reality that is more popularly called a novel. It’s not only how I see the world to be. It also makes good dramatic sense. Purely good, purely evil. Characters always dull as ditchwater. Superman is intrinsically boring. Darth Vader is intrinsically boring until a fairly clunky extra leg gets added later on in the character. To truly animate a character, your angels need demonic flex in them. Similarly, to truly make a malign predator interesting on the page and followable and more intriguing, then that demon needs compartments within him or her that are not demonic; they’re more angelic. That are at least contain the possibility of redemption. When you do this, you’re making these characters more like human beings that we know from our daily lives. And good things happen to your narrative. You want to follow them. You can start making the reader care and you cannot make a reader care about an archetype. They have to be fully fleshed into the same shades of gray, the same contradictions, the same — since they’re not just one personality, but a multiplicity of personalities. They’re all a kind of a colony, I believe. Not of one, but of [a] dominant personality who calls the shots most of the time. That’s not the whole story. There are others in there as well. Every Dr. Jekyll needs a Mr. Hyde. They’re there whether you want them to be or not. So why not invite them in when you’re making fictional people and allow them an influence. It makes the fiction better. It’s that simple.