Echo is a librarian managing the People's Library, a facility housing digitized historical figures, after previously working at the recently closed F.M. Lewis Library. She has synesthesia that causes her to see numbers as colors, a condition she actively hides from colleagues to avoid judgment. Her preference for physical books and solitary routines keeps her somewhat isolated, though she maintains a strong ethical commitment to her patrons.

Operating primarily via videoconference from Atlanta or London, he serves as Echo's direct supervisor. He directs her transition to the People's Library and oversees her interactions with the virtus. While he presents himself as a mentor looking out for Echo's best interests, he routinely withholds technical information and displays a patronizing attitude toward her capabilities.

Walter works as the custodian for the People's Library. He holds a background in mechanical engineering and decorates his personal spaces with African-inspired art. He maintains an approachable, grounded demeanor that contrasts sharply with the sterile, highly digitized environment of the library.

Jesse is a virtu residing in the People's Library, modeled after a member of the Golden Thirteen (the first Black commissioned naval officers in World War II). He exists in a confined virtual space when not checked out by patrons. Drawing on his military background, he acts as a pragmatic strategist and emotional support for Echo.

A virtu representing the 17th-century English philosopher and writer, also historically known as "Mad Madge." Housed in a virtual simulation of a northern English estate with blank books, she relies entirely on library patrons for mental stimulation. She uses her sharp intellect to analyze philosophical problems and historic concepts for Echo.

Artificial intelligence systems that facilitate daily life in Cleveland. Gina serves as a perky, highly integrated personal AI assistant handling Echo's personal logistics. Ada operates as the AI librarian managing the administrative functions of the People's Library. They represent the ubiquitous presence of limited AI designed to accomplish narrow tasks.

A former patron of the F.M. Lewis Library who struggles with the rapid technological changes in her city. She holds strong anti-AI sentiments and views the People's Library as a corrupted institution. Her dramatic actions force Echo to question the true purpose of the library's technology.

A local law enforcement officer assigned to investigate the strange disturbances occurring at the library. He relies heavily on surveillance footage to conduct his inquiries. He operates under the jurisdiction of the city but frequently coordinates with private security.

Echo's mother, who attempts to maintain a connection with her daughter despite their strained relationship. She worries about Echo's safety in a highly digitized and volatile workplace.

Echo's father, whose career as an accountant has been severely impacted by the rise of automation. His displacement by AI creates friction in his relationship with Echo, given her employment at a technologically advanced institution.

A virtu representing a 17th-century Ethiopian philosopher. He provides historical context regarding the nature of human consciousness and the traditional uses of death masks across cultures.

A virtu based on the 7th-century Indian mathematician who formalized the concept of zero. He spends his virtual existence in an isolated space until Echo queries him about the origins of nothingness.

A teenager who regularly uses the library's automated maker space to build items. He rejects the universal basic income system and harbors a cynical view of the institutions governing Cleveland.