Jack is a stay-at-home father who was fired six months ago from his job as a software programmer at MediaTronics. His professional expertise lies in agent-based computing programs that mimic the swarming behaviors of insects and predators. Thoughtful and meticulous, he is increasingly concerned by his wife's distant behavior and the inexplicable medical emergencies affecting their infant daughter.

Julia is a brilliant vice president at Xymos Technology, specializing in molecular manufacturing and technology incubation. Recently, she has grown cold, tense, and irritable, spending long hours commuting by helicopter to the Nevada fabrication plant. Her unusual behavior creates significant tension in her household, leading Jack to suspect infidelity.

Ricky is a division head at Xymos managing the molecular fabrication laboratory in the Nevada desert. Jack originally hired him early in his career, knowing him to be a charming but occasionally overpromising manager. Ricky is currently under intense pressure to deliver results on a lucrative military contract, driving him to cut corners.

Mae is a former field biologist who transitioned into software programming. She is a core member of the Xymos team and previously worked under Jack at MediaTronics. Quiet and observant, she possesses a keen understanding of real-world biological risks that her peers in computer science lack.

David is a twenty-eight-year-old engineer working at the Xymos fabrication lab. Blunt and lacking in social skills, he is highly organized and detail-oriented in his work, providing Jack with straight answers regarding the laboratory's troubled timeline.

Charley is a thirty-year-old expert in genetic algorithms. He is brilliant but socially abrasive, frequently humming, talking to himself, and aggravating his coworkers. His expertise in systems that mimic natural selection makes him vital to the Xymos project, forcing the team to tolerate his behavior.

Nicole is Jack and Julia's twelve-year-old daughter. She is perceptive to the rising tension in her parents' marriage and frequently clashes with her mother's sudden changes in parenting style.

Eric is Jack and Julia's eight-year-old son. He observes strange occurrences around the house, mentioning mysterious figures that wake him up at night and finding his electronics inexplicably broken.

Amanda is Jack and Julia's nine-month-old baby. She suffers from inexplicable, severe bruising and screaming fits that only subside when doctors place her inside an MRI machine, creating a terrifying medical mystery for Jack.

Ellen is Jack's sister and works as a clinical psychologist. She visits to offer support during his domestic troubles but frequently diagnoses his problems through a clinical lens, urging him to take decisive legal or professional action.

Bobby is a thirty-five-year-old coding supervisor at the Xymos fabrication plant. Like much of the team, he previously worked under Jack at MediaTronics and exhibits signs of extreme stress regarding the lab's current predicament.

Rosie is a programmer specializing in natural language processing at the Xymos lab. She is part of the isolated team struggling to control the facility's runaway technology under Ricky's mismanagement.

Tim is a MediaTronics employee who unexpectedly contacts Jack with a job offer. He serves as the liaison to bring Jack back to debug the PREDPREY algorithm that Xymos purchased, facilitating Jack's journey to Nevada.

Don is the head of MediaTronics. He fired Jack after Jack discovered Don was engaging in unethical business practices and an office affair, leaving Jack unemployable in Silicon Valley.

Mary is Ricky's wife. She shares Jack's concerns about the bizarre changes in her spouse's behavior, noting Ricky's strange references to black clouds and his increasing emotional distance.

Vince is a maintenance and operations worker at the Xymos plant. He provides Jack with initial warnings about the deteriorating mental state of the scientists working at the facility.

Gary is Jack's lawyer. He advises Jack to seek marriage counseling to protect himself legally in case of an alienation-of-affection custody dispute with Julia.

Annie is a headhunter operating in Silicon Valley. She provides Jack with job leads that require relocation, highlighting the fast-paced, cutthroat nature of the local tech industry.

Carol is Julia's assistant at Xymos. She exhibits signs of nervousness when interacting with Jack regarding Julia's whereabouts, hinting at the strange operations at the company.

Maria is the Forman family's housekeeper. She assists with the domestic duties while Jack manages his unemployment and Julia works increasingly long hours.

Peter is a test subject featured in a Xymos demonstration video, receiving an injection of molecular cameras to visualize his internal organs for prospective investors.