The Flies revolves around the central transformation of its main character, Orestes. While Orestes begins the play free of responsibility, commitment, and any sense of self, he soon encounters his personal freedom, accepts it, and commits himself to a value system of his choice. His transformation is an ideological one, yet manifests itself in many different ways (speech, action, even physical appearance).
The key to Orestes's transformation is the realization that memories of the past do not define the self of the present.