Through the personality of its insecure, 14-year-old protagonist, Darius Kellner, Darius the Great is Not Okay explores themes of identity, family, and mental health. Darius is a self-described fractional Persian living in Portland with his younger sister, Laleh; his mother, Shirin; and his father, Stephen. In Portland, because of his heritage and other unconventional qualities, such as his fervor for fine teas and devotion to Star Trek, Darius feels alienated from his peers and society. He often laments that though he was born in America, he doesn’t feel fully American. However, when Darius travels to Iran with his family to visit his dying grandfather for the first time, he feels he doesn’t belong there, either. This feeling is reinforced when Babou, Darius’s grandfather, voices the same sentiment about Darius. 

Darius further struggles with his fraught relationship with his father, Stephen. Stephen needles Darius about his long hair and states that Darius would have an easier time socially if he was “normal,” and Darius thus believes he’ll never measure up to his ultra-masculine father. Darius’s feelings of not belonging within his culture and family are magnified when, in Iran, Stephen watches Star Trek with Laleh, a tradition Darius believed was unique to him and Stephen alone. Darius is wounded and alienates himself further, interpreting his father’s actions as a rejection. By projecting his own insecurities onto his relationship with his father as well as with his peers at school and in Iran, Darius fulfills his fearful prophecy of “otherness.” 

It's not until Darius and Stephen talk openly about their feelings and Darius befriends Sohrab in Iran that he’s able to embrace his uniqueness and begin to feel inherently worthy, rather than feeling like an inadequate member of a certain culture, family, or social hierarchy.