Maren is a 16-year-old girl afflicted with an innate, uncontrollable urge to consume human flesh, which she refers to as the "bad thing." Abandoned by her mother, she is left to survive on her own, manage her isolation, and search for her father. She frequently reads fairy tales and identifies heavily with monsters rather than heroes.

Lee is a roughly 19-year-old fellow "eater" who rescues Maren from a dangerous situation. He travels the country in a stolen truck, possessing a pragmatic but moralistic approach to his cannibalism by only targeting people he believes make the world a worse place. He projects a tough, cynical exterior but holds deep affection for his younger sister and carries guilt over his past.

Sully is an older, unrepentant cannibal who initially claims to only eat people who have already died. He stalks Maren and presents himself as a mentor figure, arguing that people with their affliction must remain isolated from normal society. He is cynical, sadistic, and keeps a gruesome rope woven from the hair of those he has eaten.

Janelle is Maren’s mother, who spends 16 years moving from town to town to protect her daughter from the consequences of her cannibalistic urges. The strain of hiding Maren's nature drives her to heavy drinking and severe depression. She eventually reaches her breaking point and abandons Maren shortly after her sixteenth birthday, leaving only a note, some money, and a birth certificate.

Frank is Maren's absent father, whose history and whereabouts serve as the primary mystery driving Maren's cross-country journey. He was adopted as a young child after being found covered in blood at a rest stop. He is currently residing in a psychiatric hospital in Wisconsin.

Mrs. Lydia Harmon is an 88-year-old widow who kindly takes Maren in for the night after meeting her at a grocery store. She is trusting and generous, possessing a philosophy that values time and life's difficult lessons. She lives with her cat, Puss, and keeps a sphinx trophy won by her late husband.

Kayla is Lee’s younger sister. She is unaware of her brother's true nature as a cannibal but senses that something is wrong with him. She cares deeply for Lee and worries about his transient lifestyle and sudden disappearances.

Travis is an orderly at the psychiatric hospital where Frank Yearly resides. He is intensely lonely and overly invested in the lives of the "eaters" he discovers. He fixates on Maren and makes unsettling, non-sexual requests of her due to his miserable existence.

Barbara is an older woman who adopted Frank Yearly when he was six years old, following the death of her biological son, Tom. She remains emotionally distant from Frank's troubling history and is surprised to learn she has a granddaughter.

Rachel is Lee's former girlfriend. Their relationship was destroyed when she accidentally witnessed Lee killing and eating one of his mother's abusive boyfriends. The trauma left her emotionally unstable, resulting in her institutionalization.

Andy is a young Walmart employee who catches Maren shoplifting but lets her go. He invites her to his car under the guise of shared loneliness and a love of books, but his persistent, nonconsensual sexual advances lead to his demise.

Penny is a teenage babysitter who watches Maren when Maren is an infant. She becomes Maren's first victim of cannibalism when she gets too close to the baby's face, precipitating Janelle's frantic decision to flee their home.

Jason is a college student who notices Maren shelving books in the library. He is persistent in his flirting and attention, exchanging notes with her and repeatedly trying to spend time with her despite her evasiveness.

Luke is a young boy who befriends Maren at summer camp, teaching her how to float in the lake and setting up a cozy tent in the woods for them. His sweet childhood friendship with Maren ends tragically when her hunger overtakes her.

Keri-Ann is a college senior who offers Maren and Lee a ride and a place to stay in her dorm. She is highly antagonistic toward Maren while openly flirting with Lee, a dynamic that seals her fate.