Cassia is a seventeen-year-old girl with green eyes and coppery-brown hair living a comfortable life in Oria Province. She works as a sorter, using her mind to categorize numbers and data for the Society. Initially content with the strict rules governing her world, her unquestioning trust fractures when a second boy's face flashes on her official Match microcard. This glitch sparks her curiosity and initiates her slow rebellion against the predetermined path laid out for her.

Ky is an Aberration originally from the Outer Provinces, recognizable by his dark blue eyes. He works at the nutrition disposal center and lives with his aunt and uncle after his biological parents were killed. Because of his social classification, the Society forbids him from entering the Matching pool. He possesses forbidden knowledge, including the ability to write cursively and create original artwork.

Xander is Cassia's lifelong best friend and official Match. He has blonde hair and bright blue eyes, and he works at the local medical center. Confident and highly capable, Xander deeply cares for Cassia and largely follows the Society's expectations. He is highly observant and willing to bend minor rules to protect the people he loves.

Grandfather is Cassia and Bram's eighty-year-old grandfather. He holds onto secrets from the past and quietly encourages Cassia to question the world around her. Before his scheduled passing at his Final Banquet, he gives his granddaughter a golden compact containing illegal poetry. He recognizes that Cassia has the specific temperament needed to understand the forbidden words.

Abran is Cassia's father. He works as a Restorer, a job that involves sorting through historical relics in old neighborhoods to determine what has value and what must be incinerated. He loves his family deeply and occasionally skirts the edges of the Society's regulations to provide small comforts for them.

Molly is Cassia's mother, a woman with blonde hair and freckles who works at the Arboretum. She possesses a wide knowledge of plant species and frequently travels for work to inspect undocumented crops. She strictly obeys the Society's rules, believing that compliance is the only way to keep her family safe.

Bram is Cassia's ten-year-old younger brother. He is energetic, occasionally breaking minor public rules like running in the street, and he shares a close bond with his sister. He is highly attached to his family members and deeply affected by the loss of his grandfather.

Emily, often called Em, is one of Cassia's best friends in Oria Province. She experiences high anxiety about her own Match Banquet, requiring calming tablets to manage her stress before she is successfully Matched with a boy from Acadia Province.

Patrick is Ky's uncle and adoptive father. He and his wife took Ky in after their biological son was murdered in a Government building and Ky's parents died in the Outer Provinces. He attempts to provide a quiet, unassuming life for his family to avoid Official scrutiny.

Aida is Ky's aunt and adoptive mother. She adopted Ky after her sister died in the Outer Provinces. Like her husband, she lives quietly in Oria Province, trying to draw as little attention as possible from the Society.

Norah is Cassia's supervisor at her sorting job. She oversees Cassia's formal tests and monitors her progress in categorizing data, serving as a direct link between Cassia's daily work and the Society's upper administration.

Livy is a student in Cassia and Ky's summer hiking activity. She shows a distinct interest in Ky, asking him questions and occasionally provoking feelings of jealousy in Cassia as she tries to spend time with him.