Darrow is a sixteen-year-old Red who works as a Helldiver, a highly dangerous mining occupation beneath the Martian surface. He possesses rust-colored eyes, exceptional physical agility, and a quick temper. Initially content to work hard and win extra rations for his clan, a personal tragedy forces him to recognize the cruel falsehoods of the ruling Society. He undergoes agonizing physical modifications to infiltrate the Golden elite and tear down their hierarchy from the inside.

Eo is Darrow's sixteen-year-old wife and a fellow Red from the Lykos mining community. She possesses rust-colored eyes and hair, and she maintains a bold, defiant spirit despite the harsh conditions of their underground existence. She envisions a future free from slavery and consistently pushes Darrow to recognize his potential as a leader for their oppressed people.

Mustang is the Primus of House Minerva at the Institute. Small-statured but highly intelligent, she quickly proves herself to be a brilliant strategist in the war game. She holds philosophical views that differ from the typical ruthless Golden mindset, advocating for a more equitable social structure based on autonomy rather than strict domination.

Cassius au Bellona is a handsome, confident young man from a prominent Golden family. He boasts natural leadership abilities and combat skills, making him a fierce competitor for the Primus position within House Mars. He holds his family's honor in high regard and forms an early, competitive friendship with Darrow.

Archgovernor Nero au Augustus is a severe, imposing man who rules Mars with absolute authority. Belonging to an elite Gold family, he embodies the Society's most ruthless ideals regarding dominance and the necessity of subjugating the lower Colors. He manipulates the rules of society and the Institute to maintain his family's power.

The Jackal is a legendary and feared student at the Institute whose reputation for horrific tactics precedes his actual appearance. He is known for utilizing extreme psychological manipulation, starvation, and cruelty to conquer his enemies. He operates with a quiet, unhurried demeanor that masks his deeply sociopathic nature.

Sevro is a small, ill-mannered Gold, known as a Bronze due to his lower status within the ruling class. He possesses exceptional survival instincts, choosing to operate independently in the wilderness while draped in wolfskin. He relies on speed, tracking abilities, and guerrilla tactics rather than brute strength.

Dancer is a broadly built highRed with a disabled arm and leg who serves as a key leader within the Sons of Ares rebellion. He possesses a natural gravitas and extensive knowledge of the Society's true history and structure. Acting as a mentor figure, he recruits and prepares operatives to infiltrate the Golden ruling class.

Fitchner is the Proctor of House Mars at the Institute. Unlike his immaculate peers, he presents a haggard, paunchy, and unkempt appearance, often speaking profusely and brusquely. He watches over the students' war game and occasionally intervenes to offer cryptic advice or warnings about the political machinations behind the scenes.

Julian au Bellona is a young Gold student and a member of an elite, prestigious family. While he lacks the physical strength and ruthless edge of many of his peers, he possesses genuine empathy and a desire to bring honor to his house.

Titus is a brawny, physically imposing student within House Mars who quickly establishes himself as a bloodthirsty and aggressive faction leader. He operates with extreme brutality, utilizing torture and intimidation to force other students into submission. His deep-seated rage makes him a volatile and dangerous presence in the war game.

Mickey is a Violet, an artistic class within the Society, who works as a highly skilled Carver. He possesses twelve fingers and an eccentric, slightly arrogant demeanor, viewing the human body as his personal canvas. He specializes in illegal and extreme bodily modifications for high-paying or dangerous clients.

House Apollo’s Proctor is a Machiavellian Gold with a melodious, frivolous voice who oversees his students from Olympus. He is willing to break the Institute's rules and manipulate the war game's conditions to favor certain powerful families, actively interfering with students who threaten his preferred outcomes.

Tactus is a student of House Diana who belongs to an important Gold family. He wears a look of permanent derision and demonstrates a cruel, power-hungry streak, willing to betray his own allies to advance his position. He eventually faces Darrow's unique brand of justice and leadership.

Uncle Narol is Darrow's thirty-five-year-old uncle and a fellow miner in Lykos. He enjoys strong drinking and traditional dancing, often masking his deeper awareness of the Society's injustices behind a drunken exterior. He plays a crucial, covert role in helping Darrow survive the brutal realities of their mining colony.

Harmony is a masked operative for the Sons of Ares with a half-beautiful, half-scarred face. She harbors an intense, vengeful rage against the Society for past losses and takes a pragmatic, often callous view of sacrifice in the name of the rebellion. She physically trains recruits for the rigors of their missions.

Roque is a sensitive, poetic student sorted into House Mars. Unlike the purely aggressive warriors of his house, he approaches the war game with a strategic and philosophical mindset, studying the long-term implications of their violent tactics. He serves as a calm, reasoning voice among his more volatile peers.

Antonia is a beautiful and highly competitive student in House Mars. She is calculating, manipulative, and entirely self-serving, refusing to fall in line behind a single leader unless it benefits her directly. She readily employs deception and betrayal to secure her own survival and dominance.

Pax is a massive, incredibly strong student originally belonging to House Minerva. Despite his terrifying size and brute force in combat, he possesses a strong sense of loyalty. He eventually finds himself freed from slavery and enthusiastically dedicating his immense physical power to a new cause.

Lea is a shy, timid student in House Mars who struggles to adapt to the brutal, militaristic reality of the Institute. Lacking the aggressive instincts of her peers, she relies on the protection of her stronger friends to survive the internal tribal conflicts.

Matteo is a Pink who works closely with the Sons of Ares to prepare operatives for infiltration. He acts as a meticulous tutor in Golden etiquette, speech patterns, and cultural history, threatening severe consequences if his students fail to master the nuances of the ruling class.