Darkness and light are combined here into one symbol because, as the novel shows, The Duality of Light and Dark means neither can exist in isolation. As Nico and Will move through the Underworld and Tartarus, darkness is used as visual motif to enhance the theme of Trauma and Mental Health. The settings are literally dark, and this darkness can disorient and scare people who aren’t used to it, like Will. As they make their way through the dark, the teens navigate new strategies to communicate healthily and tend to their mental wellness.

However, this motif only has a meaningful effect because of the symbolic associations between darkness and negative emotions like fear, anger, frustration, jealousy, etc. Light, on the other hand, symbolizes positive emotions like optimism and hope. People should have both darkness and light within them: an imbalance to either side is not healthy. Will pulls himself out of balance in the direction of light emotions. He literally and figuratively tries to “lighten the mood” (196) in the Underworld: He thinks jokes and levity can fix this place, not understanding that darkness and light are complementary and must coexist. Nico, on the other hand, “never let anyone believe that [he] was anything but a ball of darkness” (461).