The story is built up around Darrow being so good that he's able to do what everyone else cannot. And yet he's also your average Joe in a way that I suppose is meant to make readers relate to him. The interesting thing about the story as it picks up is how despite being from this underclass and having to like remind himself constantly that these people like killed his wife. It's like the tension there is like him not letting his own like personal vendetta swamp the bigger mission of vengeance.