Karen is a sensitive twelve-year-old girl dealing with her parents' constant fighting and impending separation. She attempts to maintain a sense of order by assigning letter grades to her days in a journal given to her by her father. She desperately wishes to keep her family intact, often plotting ways to force her parents into the same room. She loves her family deeply, including her cat Mew, and tries to keep her domestic troubles a secret from her classmates.

Ellie is a stay-at-home mother who dropped out of college at nineteen to get married. She feels trapped by traditional expectations and resents her husband for controlling their household decisions. She holds a passion for refinishing antique furniture, an interest that contrasts sharply with her husband's modern tastes. She decides to find work as a receptionist to build an independent life.

Bill manages a modern furniture store that he inherited from his father. He frequently works late and expects complete authority over his household, often dismissing his wife's opinions and decisions. Despite his volatile temper and quickness to resort to name-calling, he attempts to remain present in his children's lives by taking them out to dinner and hosting them at his new apartment.

Jeff is Karen's fourteen-year-old older brother. He frequently retreats to his private 'hideaway' room to lift weights, listen to records, and talk on the phone. He presents a tough, standoffish exterior and often treats his younger sisters with disdain. Underneath his sullen teenage attitude, he feels deeply unsettled by his parents' separation.

Amy is Karen's six-year-old sister who recently started first grade. Initially energetic and fond of telling riddles, the stress of the changing household turns her into an increasingly demanding child. She frequently complains about her mother's rules and uses her status as her father's favorite to manipulate situations or demand new toys.

Aunt Ruth is Ellie's sister, older by a decade. Because of their age gap, she treats Ellie more like a daughter than a sibling, frequently offering unsolicited advice. She steps in to provide childcare, cook meals, and offer emotional support, though she also pushes Ellie to start dating again before the separation is even finalized.

Uncle Dan is Aunt Ruth's husband. He assists his wife in supporting Ellie's family through the separation, stepping in to drive the children around or make difficult phone calls during emergencies.

Garfa is Bill's father, who founded the furniture business and has since retired to Las Vegas. He holds traditional views on marriage, proudly noting that no one in their family has ever divorced. He offers to pay for a vacation to fix Bill and Ellie's relationship and shares a special bond with Karen, who reminds him of his late wife.

Debbie is Karen's best friend. Her mother keeps her heavily scheduled with daily extracurricular activities like Girl Scouts, limiting her free time. She is a loyal friend who tries to cheer Karen up by making silly monkey faces, though she sometimes inadvertently causes tension by asking about Jeff.

Gary Owens is a boy in Karen's class. He serves as Karen's primary crush, though she lacks the confidence to tell him how she feels. His impending move to Houston leaves Karen with regrets about missed opportunities.

Mrs. Singer is Karen's school teacher. Previously known for her warm and friendly demeanor, she has become remarkably strict and impatient since getting married over the summer. Her sudden change in personality adds to Karen's stress at school.

Val is a girl one year older than Karen who lives with her mother in Bill's apartment building. Because her own parents are already divorced, she possesses a mature, practical perspective on family separation. She reads the newspaper daily and consults a specific book about divorce to understand her absentee father's behavior.

Petey is Jeff's quiet and sullen friend who frequently visits to spend time in Jeff's bedroom. Karen initially finds his lack of conversation unpleasant, though she gradually grows to accept his presence in their home.

Mary Louise is Jeff's girlfriend. She expects him to keep his social commitments and refuses to tolerate his tendency to disappear without explanation when he feels stressed.

Eileen is a girl in Karen and Debbie's class. She is highly curious about community gossip and frequently asks intrusive questions about the financial implications of Karen's parents separating.