Through both aging and life experience, people change as they grow and learn. The characters of the Red Queen series have changed greatly since the beginning of the first book, and they continue to evolve throughout Glass Sword. Through the arcs of Mare, Cal, and Kilorn, Glass Sword examines who people are at any given moment and how they change over time.

Mare’s behavior and outlook on life have shifted many times since the beginning of the series. In Red Queen, the emergence of her powers brought her into the Silver world as the long-lost Lady Mareena, and forced her to learn that Silvers weren’t simply evil and power-hungry. At the end of the book, Maven’s betrayal shatters Mare’s trust, setting her up for who she is at the beginning of Glass Sword. After feeling deeply for Maven and wanting to believe change for Reds was possible with his help, Mare is now reluctant to trust anyone or anything except her own strength and power. She pushes everyone but Cal away, and she only offers Cal more trust because he was also betrayed. As the book progresses, Mare realizes that her distrust of everyone is doing her a disservice.