Carolyn is an approximately 30-year-old woman raised by an enigmatic figure known as Father. She serves as the librarian of languages, mastering countless ancient and modern tongues through intense and often brutal study. Following Father's sudden disappearance, she operates in secret to bypass a magical barrier around their neighborhood, projecting obedience to her siblings while harboring deeply buried personal ambitions.

Steve is a plumber and former skilled burglar trying to live an honest life. He carries heavy guilt from a tragic incident in his youth involving his best friend. Despite his efforts to practice Buddhist principles and avoid criminal activity, Carolyn's financial offer and subsequent framing maneuver force him back into a dangerous situation.

Father is a seemingly godlike human who has ruled the universe for thousands of years. He preserves universal knowledge within his massive Library and strictly assigns each of his twelve adopted children to study a single catalog. His sudden disappearance triggers the central conflict as his apprentices try to locate him and enter the sealed Library.

David is the librarian assigned to the catalog of war, murder, and martial arts. He wears a macabre combination of a flak jacket and a tutu, constantly smelling of blood and decay. As Father's most aggressive and dangerous apprentice, he enforces rules through extreme violence and views himself as the natural authority figure in Father's absence.

Margaret manages the catalog of death. Father frequently murders her so she can explore the underworld, a grueling process that has left her deeply traumatized. The repeated deaths and resurrections have eroded her personality, leaving her in a dissociated, zombie-like state where she smells heavily of rot.

Erwin is a Homeland Security agent and former Army combat veteran with a highly decorated record. He despises his unwanted fame as a war hero and prefers to mask his sharp intelligence behind an unpolished, foul-mouthed persona. He acts as a formidable investigator trying to untangle the strange events surrounding the missing librarians.

Jennifer is the librarian of medicine, healing, and resurrection. She bears the heavy responsibility of bringing her siblings back from the dead after Father or David kills them. She acts as an observer to the psychological damage inflicted on her family and tries to manage their extensive injuries.

Michael is the librarian of animals. He spends extensive time living in the wild with various creatures, often eschewing human customs like wearing clothing. He acts as a liaison between the human librarians and their powerful animal allies, holding a deep respect for the natural world.

Dresden is a large male lion who possesses the ability to communicate with Michael. He suffers in captivity but remains entirely focused on securing the freedom and safety of his daughter. He strikes a deal with the librarians to fight for them in exchange for a chance at liberty.

Naga is Dresden's young lion cub. She was captured from the wild after her mother was shot. She sustains severe injuries during a violent dog attack, forcing Steve to risk his own life to secure medical care for her.

Mrs. McGillicutty is an older woman whose house borders the magical barrier blocking the librarians from their home. Originally subjected to mind control, she now voluntarily houses the strange group, enjoying their company as a distraction from her own family estrangement.

Jack is Steve's childhood best friend and partner in early burglary attempts. Following a botched pharmacy robbery where he refused to implicate Steve, Jack took his own life in prison, an event that permanently altered Steve's worldview.

Detective Miner is a local law enforcement officer whose home is targeted by Carolyn. He exhibits strange, reanimated behavior before a fatal encounter sets off a chain of intense legal troubles for Steve.

Nobununga is a sentient tiger and one of Father's oldest allies. He played a crucial role in Father's rise to power thousands of years ago and commands deep respect from the librarians, particularly his apprentice.

Rachel is one of the twelve librarians, possessing unique ghost children who can see possible futures. She suffered extreme trauma as a child when Father forced her to commit unspeakable acts against her own visions.

Marcus is a wealthy hip-hop mogul who recently bought an estate in Connecticut. He holds Dresden and Naga captive in a concrete pit for his own amusement before the librarians intervene.

Larry is a public defender assigned to represent Steve Hodgson after his arrest. He tries to navigate the bizarre circumstances of the case before violence erupts in the jail.

The US President becomes entangled in the supernatural conflict after Carolyn gains access to highly classified communication channels. He must weigh the demands of the librarians against the safety of the country.