A great technique to keep readers engaged in a story is foreshadowing. That is, hinting at greater things to come and building the payoff once we get there. (A great blog by Stavros Halvatzis on this subject can be found here.) Donald Maass, literary agent and author, takes this a step further with recommending a foreshadowed set-up with the dark protagonist in the first five pages of the story. At the New York Writer’s Digest Conference 2011 back in January, he coached all the writers in the room–many of them presumably with completed manuscripts to pitch to agents–how to get readers to experience the long for change of this main character, and suggested we writers do it quickly, so to help readers get engaged from the start.
All you have to do provide HOPE to this character and put some beef behind the narrative drive is determine one way this character would like to change. Let go. What would this character like to do that is common, ordinary, or safe, so to become more human? And how can readers experience this longing for change? A dark protagonist should have something good about them we can care about.
This excellent technique was employed and refined within the first five pages of The Silent Partner.