Mallory is an eighteen-year-old former chess player who abandoned the game following a severe family trauma. She works under the table as an auto mechanic to pay the bills for her chronically ill mother and two younger sisters. Highly intelligent and fiercely protective, she struggles to accept help from others and avoids emotional vulnerability to protect herself from further pain.

Nolan is the twenty-year-old reigning World Champion of professional chess. He is deeply passionate about the game and becomes intrigued by Mallory's unique playing style after she unexpectedly defeats him. Despite his fame, wealth, and reputation as a prodigy, he remains grounded and patiently supports Mallory's entry into the professional chess circuit.

Malte Koch is an arrogant, highly-ranked professional chess player who frequently bullies others to assert his dominance. He embodies the toxic misogyny present in the chess community, acting with entitlement and routinely making inappropriate comments toward female competitors.

Mrs. Greenleaf is Mallory's mother, a freelance medical writer who experiences severe symptoms from rheumatoid arthritis. Her illness and lack of health insurance frequently prevent her from working, forcing her to rely heavily on Mallory's income. She cares deeply for her daughters and pushes Mallory to seek a normal young adult life outside of their home.

Sabrina is Mallory's fourteen-year-old sister. She is currently going through a rebellious teenage phase and frequently clashes with Mallory's strict, authoritative role in the family. Beneath her outward frustration, she deeply misses the close sibling dynamic they shared before their financial and health circumstances changed.

Darcy is the youngest daughter in the Greenleaf family. She looks up to Mallory immensely and becomes fascinated by her sister's hidden talents and competitive accomplishments. Having been very young when their father left, she is more accepting of the current family dynamic and eager to learn about the chess world.

Easton is Mallory's best friend who is preparing to move away to Colorado for college. She pushes Mallory to reengage with the outside world by guilt-tripping her into playing chess again. Their close friendship faces tension as they manage the transition into adulthood and deal with the anxiety of physical separation.

Defne is a chess Grandmaster, former professional player, and the owner of the Zugzwang chess club in New York City. Having stepped back from competitive play due to the hostile environment for women, she now mentors promising players. She recognizes Mallory's raw talent and offers her crucial guidance in dealing with the chess community.

Oz is a Grandmaster at the Zugzwang club and Defne's colleague. He shares an office with Mallory during her fellowship and provides a grumpy but highly protective presence, helping her survive the unpleasant social dynamics at professional chess tournaments.

Emil is a professional chess player and one of Nolan's closest friends. Unlike many of the hostile players in the professional circuit, he is incredibly welcoming to Mallory and asks her to join their competitive team for the Chess Olympics in Toronto.

Tanu is a female professional chess player and close friend to both Nolan and Emil. She helps create a comfortable, supportive environment for Mallory as she reenters the competitive chess scene, offering much-needed camaraderie in a highly male-dominated field.

Mr. Greenleaf is Mallory's deceased father. He originally taught Mallory how to play and love chess when she was young, but his extramarital affair and subsequent abandonment of the family left deep emotional scars on his daughter, causing her to swear off the game entirely.

Hasan is one of Mallory's high school friends. They maintain a casual physical relationship during the summer, which perfectly aligns with Mallory's strong preference for avoiding emotional intimacy and long-term commitment.