Mare is a Red who possesses a Silver lightning ability, making her a "newblood" and the reluctant face of a growing rebellion. She transitions from a powerless girl into a high-profile fugitive tasked with recruiting others like her. She carries deep trauma from recent betrayals, relying on her volatile powers to protect her family and allies from the ruling class.

Cal is a Silver prince falsely branded a traitor and forced into exile alongside the Reds he once ruled. Stripped of his royal status and military command, he relies on his fire manipulation abilities to survive. He attempts to adapt to life among rebels who despise his silver blood while seeking revenge against the brother who ruined him.

Kilorn is Mare's childhood best friend who fully commits himself to the Scarlet Guard rebellion. Unlike Mare and Cal, he possesses no supernatural abilities, relying entirely on acquired combat skills and dedication to the cause. He experiences significant jealousy and concern regarding Mare's shifting nature and her closeness with Cal.

Maven is the current ruler who claimed his father's crown through deception and violence. He uses his vast military resources to maintain a strict grip on the kingdom while ruthlessly hunting down newbloods before the rebellion can recruit them. He maintains an obsessive, psychological focus on capturing Mare.

Shade is Mare's older brother and a newblood with the ability to teleport across short distances. His power makes him an invaluable asset to the Scarlet Guard, allowing him to bypass security and move allies out of immediate danger. He maintains a confident, reassuring demeanor despite the escalating war.

Diana Farley is a dedicated captain in the Scarlet Guard who leads rebel operations on the ground. She operates without supernatural abilities, utilizing strict military discipline, tactical planning, and an independent streak to advance the cause. Her authority is challenged when she returns to the main rebel island base.

Cameron is a young newblood from a Red factory town, marked with a prominent serial number tattooed on her throat. She possesses the rare and powerful ability to silence the powers of other Silvers and newbloods. She harbors deep resentment toward the ruling class and views Mare's rebellion with high suspicion.

Jon is a mysterious newblood with the ability to see the future. He operates independently of both the crown and the rebellion, providing cryptic warnings and directions based on his shifting visions of what is to come.

The Colonel is a one-eyed military leader who commands the main Scarlet Guard island base. He represents the old guard of the rebellion, holding strict, traditional views that make him deeply suspicious of anyone with supernatural powers. He views both Silvers and newbloods as potential threats to Red equality.

Julian is a Silver who previously provided Mare with a critical list of names identifying Reds with dormant powers. Because he refuses to support Maven's regime or believe the crown's lies, he finds himself targeted and imprisoned by his own people.

Nix is a newblood with the ability to harden his skin to an impenetrable, stone-like state. He lives quietly in a Red village until Mare's group arrives. He holds a deep grudge against the Silver military for the loss of his daughters in previous conflicts.

Rash is a newblood twin who travels to the Scarlet Guard base seeking a political alliance. He represents a distant land where newbloods are purportedly accepted as equal members of society, offering a different perspective on the ongoing war.

Tahir is a newblood emissary from the Free Republic of Montfort. He works alongside his brother to convince Mare and the rebellion that a peaceful existence for newbloods is possible outside the current warzone.