Melanie is a ten-year-old girl living in an underground military facility in region 6. She possesses high intelligence and a deep fondness for Greek mythology, often imagining herself as a heroine from the stories. As a "hungry," she is infected with a pathogen that triggers cannibalistic impulses, though her cognitive abilities and self-awareness set her apart from ordinary infected individuals. She yearns for affection and carefully tracks the days to gain a sense of control over her confined life.

Helen Justineau is a teacher assigned to assess the psychological development of the infected children at Hotel Echo. She struggles to maintain the required emotional distance from her students, viewing them as human children rather than mere research subjects. Her empathy puts her at odds with the military and scientific personnel running the base.

Sergeant Eddie Parks commands the military contingent at Hotel Echo. He ensures base security by maintaining the perimeter fence and managing the daily transport of the infected children. With years of experience fighting the infected and survivalists in the wild, he strictly enforces safety protocols and views the children entirely as dangerous predators.

Dr. Caroline Caldwell is the head biologist researching the pathogen at Hotel Echo. She operates with cold detachment and prioritizes her search for a vaccine above all other considerations. She views the children strictly as biological hosts controlled by a parasite, aggressively rejecting any notion that they possess humanity.

Private Gallagher is a young soldier stationed at Hotel Echo under the command of Sergeant Parks. Raised in an abusive environment before his military service, he struggles with anxiety regarding the threats outside the perimeter fence. He relies heavily on strict adherence to orders to manage his fears.

Mr. Whitaker is an instructor at Hotel Echo who teaches math, spelling, and history to the infected children. He drinks heavily during class and suffers from depression, offering blunt answers when students ask about life beyond the base.

Miss Mailer is one of the civilian instructors at Hotel Echo. She provides routine academic exercises for the infected children as part of the base's assessment program.

Selkirk works as a laboratory assistant at Hotel Echo. She follows Dr. Caldwell's instructions closely, preparing subjects for examination and disposing of biological materials after procedures.

Marcia is a young infected child kept at Hotel Echo. She attends classes alongside Melanie until Dr. Caldwell selects her for laboratory research, after which she does not return to the cellblock.

Liam is an infected child housed in the Hotel Echo facility. He is taken to the laboratory as a test subject, allowing researchers to study how the pathogen interacts with a live host's brain.

Kenny is an infected student in Miss Justineau's class. He serves as a living example of the children's inherent danger when Sergeant Parks uses saliva to provoke his feral, cannibalistic instincts during a lesson.