Adina is a young Italian American girl growing up in Northeast Philadelphia who believes she is an extraterrestrial probe sent from a distant planet. She uses a discarded fax machine to send observational reports about human habits to her cosmic superiors. Viewing Earth from an outsider's perspective makes her highly observant but socially isolated. She struggles to understand normal human behaviors like romance and birthday rituals.

Térèse is Adina's practical and unsentimental Sicilian American mother. She works at a care facility for intellectually disabled individuals and takes on extra jobs to provide for her daughter after her husband leaves the family. Her earthly ambitions and practical concerns contrast sharply with Adina's cosmic focus.

Toni is an Italian American girl who quickly becomes Adina's closest childhood companion. She possesses a solid sense of self and an easy acceptance of others, shown by her ready acceptance of Adina's claim of being an extraterrestrial. Growing up in a large family gives Toni an understanding of interdependence that Adina lacks.

Mrs. Leafhalter is a no-nonsense, independent woman living in Adina and Térèse's apartment complex. She provides Adina with glimpses of the world outside Philadelphia, inviting the young girl to spend time at her beachfront cabin. Her self-sufficient lifestyle offers Adina an early model of how a single woman survives in the modern world.

Miguel is a pianist and artist who catches Adina's attention by using extraterrestrial language to describe his own feelings of isolation. His creative nature includes synesthesia, causing him to see shapes when he hears sounds. He introduces Adina to his musical circles but has fundamentally different views on romantic and physical connection.

Dominic is Toni's older brother who works at a Fotomat and provides an older sibling figure to Adina. He shares Adina's satirical view of the world and eventually moves to New York City. He openly identifies as queer, giving Adina language to better understand her own differences from normative society.

Solomon is an entity from Adina's home planet who serves as her mentor and instructor during her nocturnal communications. He guides her studies, helping her translate texts like *The Little Prince*, and contextualizes her mission to observe Earth.

Mark is a coworker of Térèse at the care facility who becomes her early dating interest. His presence initially disrupts the solitary dynamic between Adina and her mother, leading Térèse to spend evenings on the phone rather than helping with homework.

Amadeo is a male classmate who invites Adina to see his car right before a middle school dance performance. His expectations regarding physical intimacy conflict directly with Adina's boundaries and lack of sexual interest, leading to social friction.

Janae is a leader among the popular girls at Adina's middle school. She briefly invites Adina into her exclusive dance troupe to perform to a hip hop song, giving Adina a fleeting taste of social inclusion before kicking her out over a dispute involving a boy.

Mrs. Goldman is a vendor at the flea market who recognizes Adina's intellectual curiosity. She feeds the young girl's fascination with space by giving her Carl Sagan's *Intelligent Life in the Universe*, encouraging Adina's early academic aspirations.

Audrey is a peer of Toni and Adina who belongs to a wealthier family with a swim club membership. Her friendship with Toni turns into a bitter falling out over unreciprocated romantic feelings and social insults regarding class and appearance.

Dakota is a blonde high school classmate who serves as a foil to Adina's social struggles. She follows conventional paths of achievement, ultimately winning a city college theater scholarship that Adina also desired, despite lacking genuine passion for the subject.

Yolanda K. is an enthusiastic and encouraging gym instructor. Her classes provide Adina with a rare, reliable sense of routine and physical grounding in the sprawling, anonymous environment of New York.

Butternut is a dog Adina adopts to keep her company in the city. The pet becomes one of the most significant and consistent relationships in Adina's adult life, offering non-verbal companionship.