Geryon is a young, sensitive boy characterized as a red, winged monster living on an island. He writes an autobiography to record his inner thoughts and later turns to photography to make sense of his life. Deeply introspective and prone to crying, he hides his wings under a heavy coat and struggles to process the intense emotions he likens to an active volcano.

Herakles is an older, confident teenager who lives in a trailer park and possesses a carefree, rebellious energy. He approaches life with physical intensity and directness, viewing sex as a way to get to know someone. He paints graffiti, steals a carousel tiger from Harrods, and travels to South America to record the sounds of volcanoes.

Ancash is a young Peruvian man traveling through South America with Herakles to record the sounds of volcanoes for a documentary about Emily Dickinson. He speaks Quechua and possesses a gentle, observant demeanor. He attempts to look out for Geryon during their travels in Peru, offering him blankets and warning him about local dangers.

Geryon's Mother is a caring but somewhat distant figure who provides a sense of safety for her young son. She smokes frequently, irons clothes, and enjoys quiet Tuesday nights eating canned peaches on supper trays with Geryon while the rest of the family is out. She worries about Geryon's nocturnal habits but trusts him implicitly.

Geryon's Brother is a physically larger, older sibling who uses his size to intimidate and manipulate. He sexually abuses Geryon during their childhood, buying his silence with marbles and threats. In adulthood, he works as a sportscaster at a radio station on the mainland.

Herakles' Grandmother is an older woman living in the island town of Hades. She is prone to rambling conversations about her past, including drinking tea in Buenos Aires and meeting Virginia Woolf. She possesses a famous long-exposure photograph she took of a local volcano erupting in 1923, an image that profoundly affects Geryon.

Ancash's Mother is a resilient Peruvian woman who works as a cook for American expats. Originally from the mountain town of Huaraz, she relocated to Lima to escape guerrilla violence. She grows marijuana in a small greenhouse on the roof and acts as a confident guide when the group travels to the mountains.

Stesichoros is a historical and mythological poet whose fragmented works form the foundation of the novel's narrative. According to legend, he goes blind after writing poorly of Helen of Troy and must write a retraction to regain his sight. He appears later in the text in an imaginary interview where he discusses the nature of seeing and description.

Lazer is a philosopher attending a conference on skepticism in Argentina. He strikes up a warm conversation with Geryon over olives, discussing his young daughter and the philosophical concept of distances between people.

Hart is a local boxer residing in Hades. He spends time painting Herakles's grandmother's house alongside Herakles. He considers training Herakles to be a corner man for boxing matches.