Rune is a strawberry-blonde witch and former socialite who operates as the vigilante known as the Crimson Moth. Now a fugitive from the New Republic, she assumes the role of a loyal follower to a cruel former witch queen to protect her people. She struggles with the constant performances required to survive in a politically dangerous world. She relies on her wits and gentle blood magic to rescue other persecuted witches.

Gideon is an infamous witch-hunter and captain of the Blood Guard who serves the New Republic. Haunted by the perceived failure of falling in love with a witch, he wrestles with his loyalty to the Republic and his lingering feelings for Rune. He is a skilled combatant, deeply protective of his people, and torn between his military duty and his conscience.

Cressida is the cold, terrifying former leader of the witches. Characterized by her birch-white hair and chilling demeanor, she seeks to reclaim her throne from the New Republic and reinstate the Reign of Witches. She is calculating, possessive, and willing to use dark, sacrificial magic to achieve her political goals.

Seraphine is a maternal, mentoring figure who provides practical guidance to Rune. She operates as a loyal protector of witches but secretly disapproves of the Rosebloods' beliefs regarding non-witches. She is deeply devoted to Rune's survival and acts as a grounding presence in her life.

Soren is a royal figure in the kingdom of Umbria who commands a significant military force. He is betrothed to Rune Winters, an arrangement made primarily to secure his army for the witches' cause against the New Republic. He is wealthy, influential, and expecting a swift marriage.

Alex is Gideon's deceased younger brother and Rune's former best friend and fiancé. His recent death at the hands of Cressida leaves a profound impact on both Rune and Gideon, complicating their shared grief.

Aurelia is a powerful sibyl, a witch capable of seeing into the past, present, and future. She is coerced by the New Republic into locating surviving witches because they hold her young daughter hostage.

Meadow is Aurelia's young daughter. She is used as leverage by the Blood Guard to force her mother's compliance in hunting down other witches.

Harrow is the spymaster for the Blood Guard and a dedicated soldier for the New Republic. She harbors deep-seated bitterness toward witches due to a traumatic childhood where she was sold as a servant and mutilated by a witch family.

Noah is the Good Commander of the New Republic's Blood Guard. He is a ruthless military leader dedicated to eradicating witches and is willing to use torture and hostages, such as Aurelia's daughter, to achieve his strategic goals.

Laila is a dedicated soldier for the New Republic and Noah Creed's sister. She carries a deep hatred for witches, particularly Cressida, whom she blames for her father's death, making her rigid in her military duties.

Abigail, known as Abbie, is a non-witch and a former lover of Gideon who fought beside him during the New Republic's revolution. She is friendly, observant, and clearly harbors lingering affection for Gideon.

William is a young crew member aboard the Arcadia. He strikes up a conversation with Rune and assists her by showing her around the ship's lower decks, including the boiler room and cargo holds.

Juniper is a witch serving under Cressida's command. She is tied to Harrow's painful past, having grown up in the wealthy household where Harrow was indentured as a child.

Bart is a young aristocrat and an old acquaintance of Rune's. He harbors secrets from his family regarding his sexuality and remains neutral in the war, disliking both the Republic and the Rosebloods.

Antonio is the cook for the Wentholt family and Bart's secret lover. He possesses training in the healing arts from his time as an acolyte and is highly sympathetic to Rune and Gideon's plight.

Ava is a scar artist who works for Cressida. She uses her blood magic to etch spells into skin, a practice that forces painful compliance from her targets.