Arundhati “Aru” Shah is the protagonist of the book, and the story is told through her perspective. She is a 12-year-old Indian girl who has lived in the Museum of Ancient Indian Art and Culture in Atlanta, Georgia, her entire life. She is an only child, raised by her mother, Krithika Shah, who is a single parent. Until the events of the book, Aru had never known her biological father; he is eventually revealed to be the Sleeper, the demon released from the lamp that she lights. Aru also discovers that she is the reincarnation of Arjuna, one of the Pandava brothers from the Mahabharata, and the daughter of Indra, king of the heavens and god of thunder.

Aru has always felt like she doesn’t fit in, especially among the other students in her school, owing to them coming from far wealthier backgrounds and her culture being so different from theirs. What helps her get by is her imagination, as she presents a different, more attractive version of her life to others around her, using her imagination to spin stories based on her situation. This lands her in trouble sometimes, like when she is caught out for lying by her peers and ends up lighting the lamp to save face.