Mare is a seventeen-year-old Red living in the impoverished village of the Stilts. Facing inevitable conscription into the army, she survives by stealing to help her struggling family. Her life abruptly changes when she exhibits impossible Silver-like lightning powers in front of the royal court, forcing the King to hide her true identity to prevent a rebellion.

Cal is the crown prince of Norta, known formally as Tiberias the Seventh. He is a Silver with the ability to manipulate fire and serves as a highly skilled military tactician. Despite his privileged position, he sometimes sneaks out among the commoners in disguise to better understand the people he will one day rule.

Maven is the younger half-brother of Cal and the second prince of Norta. Like his brother, he can control fire, but he lacks Cal's status as the golden child. This secondary position makes him highly attentive to others who feel overlooked by society.

The formidable and sharp Queen of Norta possesses the terrifying ability to read and control minds. She acts as the primary architect of Mare's fabricated noble identity, ensuring the royal family's power remains unchallenged by forcing the Red girl to play a part.

Evangeline is a fierce daughter of House Samos, one of the most powerful and heavily armed Silver families. Raised to believe in her own absolute supremacy, she is ruthlessly determined to secure her place as the future queen of Norta.

Kilorn is an eighteen-year-old Red and Mare's childhood best friend. When his apprenticeship master dies, he suddenly loses his exemption from the army, prompting Mare's desperate search for a way to save him from conscription.

Farley is a stern and dedicated leader within the Scarlet Guard, a rebel organization fighting for Red equality. She orchestrates dangerous operations against the Silvers and demands a high financial price for helping individuals escape conscription.

Julian is Cal's uncle and the brother of the deceased former queen. He possesses the power of mind control through singing but holds surprisingly progressive, sympathetic views toward Reds. He becomes a vital mentor to Mare, attempting to teach her how to survive her new reality.

Rane is a unique Silver known as "the silence." His rare and highly intimidating ability allows him to completely neutralize the supernatural powers of other Silvers around him, making him an effective instructor and dangerous guard.

Gisa is Mare's younger sister, a highly skilled embroiderer who provides the primary income for their family by selling her work to Silvers. She is viewed as the golden child of the Barrow family, contrasting sharply with Mare's rebellious nature.

Shade is one of Mare's older brothers who was conscripted into the brutal war against the Lakelanders. His letters home contain subtle phrasing that eventually points Mare toward the rebel cause.

Walsh is a Red servant working quietly at the summer palace. She helps orient Mare to the overwhelming reality of serving the Silver nobility while hiding her own secret allegiances.

Will is a black-market trader operating near Mare's village. He acts as Mare's initial point of contact for reaching the Scarlet Guard when she desperately needs to smuggle Kilorn out of the country.

The King of Norta prioritizes maintaining the Silver social hierarchy and the nation's military strength against the Lakelanders. He heavily favors his eldest son, Cal, placing immense pressure on him to become a ruthless future ruler.

Lady Blonos is a Silver instructor in the royal palace who subjects Mare to hours of exhausting posture correction and education on the Silver hierarchy.