A twelve-year-old seventh grader who stands exceptionally tall at six feet three inches. Tree struggles to find a sense of belonging in the wake of his parents' split and feels burdened by societal expectations that he excel at basketball due to his size. Quiet and observant, he possesses a natural talent for fixing mechanical objects and values his deep connection with his grandfather.

A Vietnam War veteran who recently chose to have his war-injured leg amputated. He moves in with Tree and Mark to undergo physical therapy and learn how to use a prosthetic leg. Maintaining a positive outlook on life, he acts as a mentor to his grandsons and uses humor to cope with his physical challenges and painful memories.

An outspoken and confident eighth grader who refuses to tolerate bullies. Living with her aunt and an assortment of pets, she speaks her mind freely and encourages Tree to view his height as a powerful asset rather than an embarrassment. She plays the flute and attempts to maintain a connection with her emotionally distant father.

Tree's highly organized mother who recently moved out following her divorce from Mark. She tries to maintain a strong connection with her three sons through modern means like her color-coded calendars and website. Though she loves her children fiercely, her new house feels unwelcoming to Tree.

The manager of a sporting goods store who lives with Tree and Grandpa. Often disorganized and frantic, he loves his sons deeply and takes pride in them, though he struggles to balance the logistics of daily life following his divorce.

The Benton family's aging, loyal dog. Bradley offers unconditional love and emotional support to the boys, especially in the wake of the divorce. As he grows older and slower, his declining health becomes a source of worry for the family.

One of Tree's older, college-aged brothers. Athletic and formerly successful in sports, Larry struggles significantly with his parents' divorce, often masking his pain with anger, insults toward Tree, and the misuse of alcohol.

Tree's other college-aged brother. Also athletic, Curtis is generally more patient and encouraging toward Tree than Larry is. He prefers to keep his own struggles—such as financial missteps at school—hidden from his parents to avoid conflict.

Tree's basketball coach, who holds the firm belief that tall boys inherently possess athletic talent. He constantly pressures Tree to excel on the court and mandates unusual training methods, such as ballroom dancing, for the team.

A student and teammate who frequently bullies Tree for his height and lack of athletic prowess. He looks for opportunities to put others down.

A tough, encouraging physical therapist who helps Grandpa learn to navigate life without his leg. She challenges him to focus on his strengths rather than his physical losses.

A fellow Vietnam veteran who attends physical therapy with Grandpa. Despite occasional disagreements over limitations, he is a supportive friend who helps Grandpa honor their fallen comrades.

Tree's best friend. Sully wears hearing aids, a physical trait that helps him understand and empathize with Tree's efforts to accommodate Grandpa's new disabilities.

The school janitor who reluctantly bends the rules to allow displaced pets into the school basement during a severe flood.

Sophie's absent father, who rarely shows warmth or affection. He frequently forgets to bring her gifts and appears disconnected from her life, yet Sophie makes a point of maintaining contact with him.

Sophie's aunt, who lives with the eighth grader. She attempts to keep Sophie's bold temper in check but cares for her deeply.

An uninteresting man who takes Tree's mom out on a date, much to the dismay of her sons and her dog.

Jan's energetic and somewhat hostile dog. He guards the new house aggressively and makes Tree feel unwelcome.

Sophie's pet iguana, who begins to slow down due to age.

Tree's friend whose sister develops an allergy to his foul-mouthed parrot, Fred.

A grumpy parrot temporarily living with Tree's family. He routinely tells people to back off, prompting Grandpa to try to teach him manners.

A neighbor of the Bentons who occasionally drops by with baked goods. She has a cat that acts as the nemesis to the Benton family dog, Bradley.