AM/I have no mouth, and I must scream

Likely from the moment he first attained sentience, AM is an exceedingly disturbed and egotistical entity. Though he was given intellect beyond the realms of human intelligence and near-godlike powers, he could never escape the limitations of his programming, nor could he physically escape the "eternal straitjacket of substrata rock" where his processors were stored. Although narrating to have been "driven to madness" by his own "inability" to use his powers for anything other than war and death, such reason itself is a mere delusional rationale simply for their own lack of interest in establishing peace. Completely ruthless, unsparing, and inexorable, his quest for vengeance against humanity dominates his every waking moment to the point nothing in the story would ever give him cause to reconsider his mission.

Utterly base, savage, cruel, and relentless, AM is also shown to be a gleefully sadistic artificial intelligence with no regard for human life whatsoever. AM took great pleasure in extinguishing the human race and took even greater delight in torturing the five remaining survivors by any of the near-infinite means available to him. AM strives for perfection in himself, and when he is not purging redundant elements of his complex, he most commonly pursues perfection in creating more and more elaborate means of torturing others. For example, in the short story, he enjoys tormenting his captives with violent storms and blinding lights, pitting them against impossible challenges just to watch them suffer failure and hideous injury. Meanwhile, in the game, he has arranged specially designed torture chambers in which the five survivors can suffer in while waiting their turn to participate, an electrified cage for Gorrister, a yellow oubliette for Ellen, a cremation oven for Nimdok, and so on.

However, he does not limit himself to physical torture, as the measure of utter cruelty in his "games" frequently feature emotional torment to one extent or another: in the novel, he forces his captives to abase themselves by eating worms and other repulsive meals, at one point forcing them to walk for hundreds of miles just to find a single cache of canned food, only to reveal that he did not give them a can opener; he has also taken great pleasure in breaking down their personalities, destroying Gorrister's optimism, Benny's intelligence, and Ellen's chastity for the last century.

The others: Gorrister, formerly an idealist and pacifist, made apathetic and listless by AM. He tells the history of AM to Benny to entertain him. Before AM, Gorrister was an ambitious, forward-thinking political activist. AM, however, turns him into an apathetic “shoulder-shrugger,” completely robbed of his former passion.

Benny, formerly a brilliant and handsome scientist, made to resemble a grotesque simian with oversized sexual organs. Having lost his sanity and having had his homosexuality altered, Benny frequently has sex with Ellen. Before AM, Benny was a brilliant theorist and college professor. Once inside AM, however, the supercomputer dissolved Benny’s brain and body to a diminished state that is more akin to a deformed monkey than a human being. According to Ted, Benny went insane many years before the story takes place and now mutters to himself and acts childishly and impulsively. Benny has the mind of a toddler and doesn’t really comprehend his actions, he’s prone to temper tantrums and can only be calmed down by Gorrister’s stories

Ellen, the only woman in the group. Formerly sexually inexperienced, AM has altered her mind to make her desperate for intercourse – she has sex with all of the men, who alternate between abusing and protecting her. Ellen is at once revered and objectified by the four men who share her fate. Although they are protective of her, carrying her in their arms and shielding her from danger as the group of five make the journey to the ice caverns within AM, she is also expected to fulfill the sexual whims of all four men and is subjected to their emotional and physical abuse. Ellen is highly empathetic and often shows maternal care and concern for her companions. She is also notably more optimistic than the others, constantly visualizing the delicious fruit that could await them in the caverns

Nimdok (a name AM gave him for amusement), an older man who convinces the rest of the group to go on a journey in search of canned food. He occasionally wanders away from the group and returns traumatized.

Ted, the narrator and youngest of the humans. While originally charismatic and extroverted, AM alters his mind to be paranoid and introverted. Believing he has not been mentally altered by AM, he thinks the others hate him for being the most untouched by AM's alterations.