Clary is a sixteen-year-old artist struggling with the recent discovery that she is a Shadowhunter. Petite with curly red hair and green eyes, she currently lives with Luke Garroway while her mother remains in a coma. She feels overwhelmed by the sudden dangers of her new life and the shocking claim that Valentine is her father.

Jace is a seventeen-year-old Shadowhunter living at the New York Institute. Raised by Valentine until age ten, he uses an abrasive, sarcastic demeanor to hide his vulnerability. He actively suppresses his romantic feelings for Clary following the claim that they share the same father.

Simon is Clary's sixteen-year-old mortal best friend. He wears glasses and enjoys pop culture. He harbors a deep, long-standing affection for Clary and courageously enters the perilous Shadowhunter society strictly to remain close to her.

Valentine is a disgraced, rogue Shadowhunter who formerly led a radical faction known as the Circle. He believes Downworlders are impure and seeks to cleanse the Shadowhunter society. He utilizes the stolen Mortal Cup and manipulates demons to build an army.

Luke is a bookstore owner and the leader of a Manhattan werewolf pack. He formerly fought as a Shadowhunter and Valentine's parabatai before being bitten. He acts as a dedicated protector and surrogate parent to Clary while her mother is comatose.

Magnus is the High Warlock of Brooklyn. He is over four hundred years old but physically presents as a nineteen-year-old. He frequently wears glittery clothing and maintains an ironic front while providing essential magical healing to the Shadowhunters.

Isabelle is a sixteen-year-old Shadowhunter who fights in dresses and high heels. She is quick-witted and highly protective of her adoptive brother Jace, often fighting while heavily armed. She prioritizes immediate family loyalty above the governing laws of the Clave.

Alec is an eighteen-year-old Shadowhunter and the oldest of the teenage group. He tends to be quieter and more secretive than his sister Isabelle. He acts strategically to protect his siblings when dealing with Clave authorities.

Maryse is the head of the New York Institute. She formerly belonged to Valentine's Circle and now attempts to maintain strict adherence to Clave laws to protect her family's standing. Her lingering shame causes her to act coldly toward Jace to divert suspicion.

Maia is a fifteen-year-old werewolf who recently joined Luke's Manhattan pack. She moved to the city to escape discrimination in her suburban hometown. She carries trauma from an abusive former relationship and a deceased older brother.

Imogen is the Inquisitor for the Clave, an intimidating woman tasked with investigating Shadowhunter compliance. She harbors deep bitterness from the loss of her son and relentlessly suspects Jace of acting as Valentine's spy.

Jocelyn is Clary's mother and a former member of Valentine's Circle. She currently lies in a self-induced coma in a mundane hospital, having used magic to prevent Valentine from accessing her memories.

Max is the nine-year-old youngest child of the Lightwood family. He resides at the Institute and requires supervision when his older siblings leave for dangerous missions.

Robert is the patriarch of the Lightwood family. He assists in running the New York Institute alongside his wife Maryse, attempting to maintain order during the demon attacks.

The Queen is the local ruler of the Fey. She holds an audience with the teenage Shadowhunters and forces them to play dangerous psychological games to secure her assistance.

Raphael is a vampire leader in New York City. He communicates with the Shadowhunters to ensure his clan is not wrongfully blamed for the recent string of Downworlder murders.

Agramon is a powerful fear demon summoned by Valentine Morgenstern. It takes the physical form of its victim's deepest terror to incapacitate them during combat or interrogation.