Sasha is a 23-year-old survivor who works in the physically demanding Expansion Sector. She previously served in the Hospital Ward, where her habit of sitting with terminal patients earned her the nickname "Death's Angel." Haunted by the deaths of her parents and two younger siblings during the war, she maintains a hardened exterior and actively avoids emotional attachments. Her exceptional marksmanship results in her forced recruitment into the elite Force Unit Seven.

Tristian is the commander of Unit Seven within the Force. Unlike other commanders in Haven, he actively fosters a sense of family and mutual reliance among his subordinates. He possesses a long, complicated history with Force Commander Lyssa Burdon, creating ongoing political friction for his team. Recognizing Sasha's medical talent, he relentlessly pursues her recruitment to safeguard his unit.

Levi serves as Tristian's second-in-command and acts as Sasha's field partner within Unit Seven. A former foster child, he demands total commitment from his recruits and pushes them to their physical limits. Beneath his reserved, stern demeanor, he possesses a strong empathy that helps him understand Sasha's suppressed grief.

Burdon is the formidable Commander of the Force who rules with paranoia and vindictiveness. She views Unit Seven's loyalty to Tristian as a direct threat to her authority. Utilizing her rank, she frequently manipulates assignments and missions to settle personal scores and consolidate her control over Haven.

Kaleo commands Unit Five, one of the elite Exploratory Units competing for surface resources. He takes an uncompromising approach to his missions and openly antagonizes Unit Seven. His alignment with Commander Burdon affords him special privileges and stokes intense animosity between his team and Tristian's.

Dr. Kumar is a mentor from Sasha's time in the Hospital Ward. He is one of the few individuals who sees past her hardened facade to recognize her medical talent. He operates a quiet rebellion against Haven's cruel health-score system by secretly allowing Sasha to alter charts and treat low-ranking patients.

Ingrid is a fierce member of Unit Seven who directs intense hostility toward Sasha. Her anger stems from unresolved grief over her former partner Lily, who died after Sasha transferred her to the official Ward. Ingrid views Sasha's presence on the team as a painful reminder of this loss.

Damien functions as the primary comic relief within Unit Seven, utilizing constant jokes to lighten the bunker's grim reality. He was abandoned by his cousins during the war and forced to walk alone to Haven. He secretly suffers from a severe, chronic ankle injury that he hides to preserve his health score.

Isla is a relentlessly optimistic member of Unit Seven. She actively seeks to befriend Sasha from the moment she joins the team. Her cheerful demeanor often masks the inner turmoil caused by her complicated romantic history with two of her teammates.

Patrick is Unit Seven's logical and methodical strategist. He is highly concerned with Force history, rules, and protocol. A devout Catholic who constantly wears a cross, he struggles to reconcile his moral beliefs with the violent necessities of surface missions.

Rumi is the quiet, meditative observer of Unit Seven. She rarely sleeps through the night and spends much of her time watching the interpersonal dynamics of her teammates. Her silence is often mistaken for aloofness, but she possesses exceptional deductive skills regarding those around her.

Jaxon is an arrogant and opportunistic member of the Force. He initially maintains a strictly physical arrangement with Sasha, which she abruptly ends upon joining Unit Seven. He views relationships as conquests and frequently seeks opportunities to publicly humiliate Sasha and her new unit.

Noah Henderson commands Force Unit Twelve. He gathers intelligence on the surface and reports significant changes in radiation levels. He maintains a romantic relationship with a member of Tristian's unit.

Bretta is Ingrid's younger sister who lives and works in the Kitchens sector of Haven. Because of her low health score, she is officially barred from receiving care in the Hospital Ward when a severe illness sweeps through the bunker.

Lily is a deceased former member of Unit Seven. She contracted a terminal illness and was transferred to the official Hospital Ward by Sasha, where she ultimately died. Her death deeply fractured the camaraderie of the unit.

Eli is Sasha's deceased younger brother. He was murdered by an intruder during the apocalyptic aftermath of the war. His death continually haunts Sasha, causing her to freeze during tactical simulations that involve hostages.

Lara is Sasha's deceased younger sister. She survived the war long enough to reach the underground bunker but died of illness shortly after arriving in the Hospital Ward.

Julia is Sasha's deceased mother. She harbored intense resentment toward Sasha because the girl physically resembled her absent military husband. During the war, Julia gave up and died of grief, leaving her children to fend for themselves.

Sasha's deceased father was an Army Special Forces soldier who taught her comprehensive survival and combat skills before shipping out to fight in the war. He correctly anticipated the grim realities of the post-war world and ensured Sasha was equipped to survive it.

Dr. Uri Foster is the senior leader of Haven's Hospital Ward. He strictly adheres to the bunker's health-score system, frequently dismissing severely ill patients to preserve resources. He aligns himself with the bunker's political leadership to maintain order.

Leon Terral is the leader of the Expansion Sector, which is responsible for digging new tunnels in the underground bunker. He manages the lowest class of laborers and maintains covert operations beneath Haven.

Murray is a member of Jaxon's Force unit. Seeking a promotion promised by Commander Burdon, he launches a vicious physical attack against Sasha during a sparring session.

Tate is a Sanitation worker who orchestrates an attempted assault against Sasha in the tunnels. His attack is swiftly and brutally dismantled when Sasha pins him and threatens his life.