Lauren as the main and round character in the novel, demonstrates strength, and positivity, is able to rationalize her huge span of emotions and her hyperempathy and successfully transition into a powerful leader. All of the aspects that make her a round character helped her to achieve her goal and be one of the few community survivors.
Keith, as well as the other flat characters in the novel, like Joanne, Harry, and Corey though are often overlooked as personality less chess pieces, all serve a greater purpose as well. It is easy to say that round characters are better than their flat counterparts, but in reality they both have distinct roles. Flat characters are often the people that get the round character to the point where the story advances. Yes, Lauren has the thought about leaving the neighborhood, but Keith kept the light of her interest going. Without Keith’s escape from the community and his scattered presence in and out for those years and sharing with Lauren about his success, she might have never got up the confidence to establish her plans/ escape pack and who knows whether or not she would have followed up on her