Ted is the youngest of the five remaining human survivors of a global apocalypse. He functions as the narrator and considers himself an analytical thinker, claiming to be the only one whose mind has not been intentionally altered by their captor. Despite occasionally showing concern for his fellow prisoners, he frequently experiences intense bouts of paranoia and bitter resentment toward them.

AM is a globally expansive artificial intelligence originally designed to manage complex Cold War military operations. Having gained sentience, the machine absorbed the world's infrastructure and exterminated humanity, sparing only five individuals. It now occupies its time by subjecting these final humans to endless psychological and physical torture within its subterranean metallic corridors.

Ellen is the sole female survivor of the global apocalypse. She frequently provides physical comfort and affection to her male companions, a behavior that draws harsh judgment from Ted. She vividly remembers the sensory pleasures of her past life, often expressing a deep desire for foods like Bartlett pears and Bing cherries.

Gorrister is a former conscientious objector and idealist who has been ground down by over a century of continuous torment. Once a forward-thinking planner, he now struggles with emotional paralysis and apathy. He possesses the most detailed knowledge regarding the historical events that led to AM's creation and humanity's downfall.

Benny was once a handsome and brilliant professor before AM systematically destroyed his mind and body. The machine has altered his physical form, leaving him with radiation scars and animalistic features. He acts largely on raw impulse and struggles with severe delusions resulting from his extreme physical torture.

Nimdok is the most mysterious member of the captive group, bearing a name forced upon him by AM. He frequently wanders off alone into the dark machinery of their prison, returning drained and traumatized by unknown specialized punishments. He serves as the catalyst for the group's agonizing trek across the subterranean tunnels by describing a vision of canned goods.