John is a 75-year-old former advertising writer from Earth who joins the Colonial Defense Force for a chance at a new, younger life. Practical and observant, he approaches the bizarre and brutal reality of intergalactic warfare with a grounded perspective. He receives a genetically modified body and must adapt to combat while questioning the morality of the human expansion effort.

Jane is a highly skilled, genetically modified soldier in the Ghost Brigade, the elite special forces of the CDF. Born directly into the military with no memories of a civilian life, she is calculating and tactically brilliant. She handles her lack of a human past by asking questions about life on Earth, slowly opening up to the concept of personal connection.

Harry is a former physics teacher from Earth who enlists in the CDF alongside John. Highly intelligent and inquisitive, he serves as the group's unofficial scientific expert, frequently speculating on the advanced technology the Colonial Union keeps hidden from Earth. He routinely questions the motives of the military hierarchy.

Luisa is a tactical and capable corporal in the CDF. Originally from Peru, where her family was killed in a military coup, she carries a profound understanding of violence and politics. She privately believes the CDF relies too heavily on force instead of diplomacy but follows orders with the intention of eventually rising through the ranks to change the system.

The Consu are a highly advanced, fiercely territorial alien species that serves as a primary adversary for the CDF. Unlike other alien races fighting purely for territory, they engage in warfare driven by complex religious rituals. They intentionally match their combat technology to their opponents to ensure a fair fight, viewing war as a means of uplifting other species toward spiritual perfection.

Katherine is John Perry's deceased wife. She and John originally signed up for the CDF together at age 65, but she died of a stroke before reaching the actual enlistment age. Her memory remains a strong anchor for John.

Charlie is John and Katherine's adult son, who remains on Earth with his own wife and child. He initially resented his parents' decision to enlist in the military but eventually reconciled with John before his departure.

Jesse is a determined recruit who joins the CDF primarily to travel and see the universe before she dies. She bonds quickly with John and Harry during their journey to the Colonial Station, forming the core of their tight-knit friend group.

Alan is a former theoretical physicist who becomes one of John's closest friends and squadmates in the CDF. He marvels at the constellations in deep space and supports John through rigorous basic training, utilizing his intellect to help their squad succeed.

Maggie is a former professor of philosophy and religion who joins John's friend group. She brings an academic and analytical perspective to the recruits' bewildering transformation into genetically enhanced soldiers.

Thomas is a former doctor who uses his medical background to hypothesize about the CDF's mysterious physical upgrade process. He becomes part of John's extended circle of friends during training.

Susan is a recruit who joins John's circle of friends. She provides insightful theories about why the CDF makes all the recruits highly attractive, suggesting it builds implicit trust and devotion among the soldiers.

Antonio is the brutal, exacting commander of John's basic training platoon. He initially targets recruits based on their backgrounds to weed out weakness. He harbors a surprising personal connection to one of John's old advertising campaigns, which earns John his grudging respect.

Leon is an abrasive and prejudiced man from Chicago who is assigned as John's initial roommate. He alienates the other recruits with his racist remarks before the physical transformation process begins.

Dr. Russell is a pragmatic, unsentimental medical doctor tasked with evaluating the recruits and overseeing the consciousness transfer process. He views the recruits' original human bodies with strict clinical detachment.

Lieutenant Colonel Higgee is the commanding officer who formally welcomes the recruits and later delivers the sobering reality of their mission. He outlines the staggering casualty rates they will face in the intergalactic war.

Thaddeus is a former ambassador and senator who struggles to adapt his diplomatic mindset to the realities of the CDF. He firmly believes in attempting peaceful negotiations with alien species rather than relying solely on military force, often frustrating his superiors.

Major Crick is the commanding officer of the Ghost Brigade's special forces ship. He operates with the quiet efficiency typical of the heavily modified special forces soldiers, relying on neural communication over spoken words.