Violet is a 20-year-old cadet at the Basgaith War College. Originally trained to join the Scribe Quadrant, she is physically smaller and frailer than her peers due to a childhood illness. Despite her mother forcing her into the lethal Rider Quadrant, Violet relies on her sharp intellect, extensive historical knowledge, and cunning to survive the grueling physical challenges. She values human life and maintains a strong personal code of ethics.

Xaden is a third-year rider and the wingleader of the Fourth Wing. He is the son of Fen Riorson, a separatist leader executed for treason. As punishment for his father's actions, Xaden and the other children of the separatists are forced into the Rider Quadrant and marked with relic tattoos. He is an exceptionally skilled shadow-wielder who projects a cold, intimidating exterior to protect the marked cadets under his command.

Dain is a second-year rider, a squad leader, and Violet's childhood friend. He is deeply committed to the rules of the college and the laws of Navarre. Fearing for Violet's life, he repeatedly attempts to convince her to transfer to the Scribe Quadrant. His rigid adherence to military protocol frequently clashes with Violet's growing independence.

Rhiannon is a pragmatic, capable first-year cadet from a small town near the kingdom's border. She excels at hand-to-hand combat and quickly proves herself as a physically capable recruit. She trades physical combat lessons for Violet's historical tutoring.

Jack is a massive, exceptionally brutal first-year cadet who thrives on the violent culture of the Rider Quadrant. He murders fellow recruits within his first day and immediately singles out Violet as a target due to her physical size. He relies entirely on his brute strength and cruelty to establish dominance.

Liam is a highly skilled, muscular first-year cadet who bears the relic tattoo of the rebellion. Despite his traumatic upbringing and forced conscription, he maintains a surprisingly steady demeanor. He serves in a protective capacity within the Fourth Wing, assigned to shadow Violet.

General Sorrengail is the commanding officer of Basgaith War College and one of the highest-ranking military officials in Navarre. She is cold, strict, and deeply concerned with her family's military legacy. She views Violet's scribe training as a weakness and forces her daughter into the deadly rider trials to uphold the family name.

Mira is Violet's older sister and an active, proven dragon rider. She is fiercely protective of Violet and deeply critical of their mother's decision to force her into the quadrant. Before returning to the front lines, she provides Violet with modified armor and practical advice for surviving the initial trials.

Brennan is Violet's older brother who died in battle five years prior to the events of the novel. Before his death, he was an exceptional rider and a skilled mender. He left behind a detailed notebook filled with strategic advice that becomes instrumental to Violet's early survival.

Tairneanach, known as Tairn, is a massive black dragon. He is an ancient, formidable presence among the dragons at the war college. He is fiercely intelligent and holds significant influence over the dragon hierarchy.

Andarnaurram, or Andarna, is a rare golden feathertail dragon. Much smaller than the other dragons in the valley, she is frequently targeted by ruthless cadets who view her as an easy kill during the bonding trials.

Sgaeyl is a vicious, powerful navy dragon. She is highly protective of her rider and shares a deep, mated bond with the black dragon Tairn, which heavily influences the politics of the dragon riders.

Imogen is a second-year cadet who bears the rebellion relic. She harbors deep-seated anger toward the Navarre government and the Sorrengail family in particular. She uses her uncanny speed and physical superiority to punish Violet during their sanctioned sparring matches.

Jesinia is a dedicated scribe and a former colleague of Violet's. She represents the quiet, scholarly life Violet was forced to leave behind and continues to assist Violet with acquiring books and scrolls.

Ridoc is a first-year cadet who quickly establishes himself as the class clown. He uses humor to deflect the intense pressure of the college and stands up for his squadmates during stressful training exercises.

Sawyer is a repeating cadet who joins Dain's squad. He helps train Violet in hand-to-hand combat in exchange for her assistance with the college's grueling academic history exams.