Hayley is a 17-year-old high school senior who recently transitioned from living on the road to attending a traditional high school. She is highly protective of her father and hypervigilant, often applying a militaristic threat-assessment mentality to her daily life. Burdened by her family's struggles, she uses humor and isolation to cope with her overwhelming responsibilities.

Andy is a veteran of the wars in Iraq and Afghanistan who is deeply haunted by his traumatic experiences. He struggles to maintain employment or handle daily responsibilities, retreating into isolation in his childhood home. He attempts to self-medicate with alcohol and drugs, leading to increasingly erratic behavior.

Finn is an intelligent, quirky high school student and former swimmer who is passionate about the school newspaper. He is observant and acts as a grounding presence for Hayley, despite dealing with his own hidden family struggles regarding his sister's addiction. He uses humor to connect with others and diligently pursues his academic goals.

Gracie is Hayley's childhood friend and neighbor who helps her readjust to a traditional high school environment. Outgoing and seemingly put-together, Gracie secretly struggles with her parents' constant fighting and separation. She occasionally misuses prescription pills to cope with her unstable home life.

Trish is Andy's ex-girlfriend who acted as a mother figure to Hayley during her early childhood. Now working as a nurse and maintaining her sobriety, she attempts to re-enter Andy and Hayley's lives to offer help and support. She faces intense hostility from Hayley but remains persistent in her efforts to assist the family.

Ms. Benedetti is the high school guidance counselor who monitors Hayley's progress. She is genuinely concerned about Hayley's poor grades and unconventional home life. She repeatedly tries to intervene by contacting Hayley's father and discussing college applications.

Roy is an army friend of Andy's who is deeply concerned about his deteriorating condition. He visits the house with other soldiers to build a fire pit and check on his friend. He tries to encourage Andy to get professional help and reaches out to Trish when his direct efforts fail.

Mr. Cleveland is Hayley's precalculus teacher and the supervisor of the school newspaper. He is strict and highly critical of Hayley's academic performance and classroom attitude. He eventually assigns Finn to tutor her as a condition for keeping the newspaper running.

Topher is Gracie's high school boyfriend. He frequently finds himself arguing with Gracie, who projects her anxieties about her parents' infidelity onto him. He maintains a friendly demeanor toward Hayley during their lunch periods.

Michael is an old high school friend of Andy's whom Hayley intensely dislikes. He acts as a negative influence, selling marijuana to Andy and enabling his substance abuse. He frequently lingers around the house, much to Hayley's discomfort.

Doris is an elderly woman at St. Anthony's Nursing Home where Hayley completes her community service. She suffers from dementia and constantly asks for her sister, who died seventy years ago. Her condition prompts Hayley to contemplate the nature and value of memory.

Rebecca is Hayley's biological mother and Andy's late wife. She was a parachute instructor who died in a car accident when Hayley was a baby. Her absence leaves a profound void in both Hayley and Andy's lives.