Christine Blake, often called Chris, is a central figure in the Lazarus team, assembled to prevent a global catastrophe. Her outward demeanor is that of a cheerful and frank woman, possessing the easy-going mannerisms of an older sister who interacts openly with everyone around her. Beneath this accessible and fearless exterior, however, she carries a deep well of personal pain and heartbreak, a consequence of her shadowy past. She is described as irreverent and impatient with conventional expectations, living life on her own terms.

Christine's background is one of deliberate reinvention. Her real name is Alexandra, and she was once a spy in the employ of the Russian government, working for a secret agency. Known by the affectionate diminutive Sashenka, she was part of a world of state secrets and covert operations. Her life changed during a catastrophic incident at an airport, where a firefight led to the release of a deadly poison. Almost everyone present was killed instantly, but Christine was one of the few survivors. Later, while in a hospital, she was caught in a fire and briefly flatlined. When her name appeared on a list of fatalities, she seized the opportunity to escape her former life. She changed her name to Christine Blake, altered her appearance, and effectively erased her identity as Alexandra.

Her motivations are rooted in survival and a desire for freedom from the control of her past. The Lazarus team’s handler, Hersch Lindemann, selected Christine for the team specifically because of her skills as a defected Russian special agent. In the story, Christine serves as the team's gun specialist, handling all kinds of firearms with notable skill. Her past, however, is not easily left behind. Her former colleagues, who do not forgive her betrayal, capture her. This event reveals that one of these pursuers, Inga, was not just a fellow agent but also a former romantic partner. Inga was devastated by Christine's apparent death and subsequent abandonment, leading to a complex and tragic confrontation during Christine's rescue. Despite the team having worked together for less than a month, they demonstrate profound loyalty by risking their lives to save her, reinforcing that her past is irrelevant to the person she is now and the bond they share.

Christine's key relationships are defined by this duality of past and present. Her connection with Inga is the most poignant, a lost love shattered by the demands of their espionage careers, which ends in tragedy when Inga is fatally shot before they can fully reconcile. Within the Lazarus team, her relationship with Axel Gilberto, the Brazilian parkour expert, is central. During her rescue, when she insists she is not worth the danger, Axel refuses to leave her behind, stating he cares about who she is in the present, not her history as a spy. This act of loyalty helps her begin to accept her new identity. Her relationships with other teammates, like the hacker Eleina and drone pilot Leland, are also strong, as they all participate in her rescue.

Throughout the series, Christine undergoes significant personal development. While initially portrayed as a carefree and skilled operative, the confrontation with her past forces her to confront the trauma and loss she has been running from. The death of Inga, who in her final moments tells Christine to live her life for the both of them, serves as a catalyst for her to fully commit to her new path, embracing her current family in the Lazarus team. Her development moves from a woman fleeing her history to one who, through acceptance and grief, is able to build a future. Beyond her expertise with guns, Christine is a highly capable combatant, able to fight effectively even while restrained. She is also noted to be a heavy drinker, and like the other members of Lazarus, she was one of the five survivors of the airport disaster, which granted her a natural resistance to the toxic effects of the Hapna drug that threatens the world.