Auden is an eighteen-year-old high school graduate and academically brilliant insomniac. She grew up acting as a little adult during her parents' competitive marriage and subsequent divorce, resulting in her missing out on typical childhood experiences. She spends her nights reading at a 24-hour diner to cope with her inability to sleep. She accepts a summer invitation to the beach town of Colby to stay with her father, hoping to step outside her comfort zone before attending Defriese University.

Eli is a twenty-year-old former professional BMX biker who works at a local bike shop in Colby. Following the death of his best friend in a car accident, he quit professional biking and became reclusive, avoiding social events he previously enjoyed. He struggles with insomnia and frequently spends his nights awake around town. Eli connects with Auden over their shared sleeplessness and initiates a quest to help her experience the childhood activities she missed.

Victoria is a prestigious professor of Renaissance literature known for her sharp wit and academic rigor. She holds a superior attitude toward those she considers less intellectual and frequently dismisses traditionally feminine interests. Following her divorce, she keeps her emotional distance from others and maintains casual relationships with graduate students. She expects Auden to focus solely on academic achievements and views social distractions as foolish.

Robert is a novelist and writing professor who lives in the coastal town of Colby. He is entirely consumed by the novel he has been writing for ten years, using his creative work as an excuse to avoid parenting responsibilities. He manipulates conversations to make his selfish choices appear necessary, heavily relying on his new wife to manage their household and infant daughter. He frequently retreats to his study rather than engaging with his family.

Heidi is Robert's twenty-six-year-old wife and the owner of a trendy boutique called Clementine's. She struggles to care for her colicky newborn without assistance from her husband. Though she presents an outgoing and hyper-feminine appearance that Auden initially judges, she is actually a highly organized and capable businesswoman. She genuinely wants Auden to feel welcome in their home and encourages a relationship between Auden and her father.

Thisbe is the newborn daughter of Robert and Heidi. She is an extremely fussy infant who cries constantly and requires high-volume wave sounds to sleep. Her constant needs cause tension in the household and highlight Robert's reluctance to participate in child-rearing.

Hollis is Auden's older brother, a spirited and energetic young man who spent his childhood getting into trouble. Unlike Auden, he coped with their parents' divorce by traveling around Europe and Asia, maintaining a fun-loving attitude. He values emotional connections and encourages his sister to embrace new experiences outside of her studies.

Maggie is a friendly teenage clerk at Clementine's who balances a stereotypical girly exterior with surprising financial intelligence and a passion for BMX biking. She is preparing to attend the same prestigious university as Auden. Maggie serves as Auden's entry point into the local social scene, breaking down Auden's prejudices about female friendships.

Adam is a cheerful teenage BMX rider who works at the local bike shop with Eli. He embraces life with enthusiasm and frequently organizes social gatherings, like hot dog parties, for his friend group. He serves as an encouraging presence in the local biking community and tries to bring his friends together.

Jake is Eli's younger brother, a brash and confident local boy who enjoys attention from girls. He acts impulsively and often lacks the maturity of his older brother, pursuing casual hookups at beach parties.

Esther is a teenage employee at Clementine's and part of Maggie's close-knit friend group. She enjoys gossiping, dancing during quitting time, and attending local parties, representing the carefree teenage experience Auden missed.

Leah is another clerk at Heidi's boutique. Alongside Esther and Maggie, she forms a tight trio of friends who bond over fashion, boys, and local gossip. She is welcoming to Auden despite their different personalities.

Jason is Auden's former high school classmate and academic rival. He is intensely focused on his college preparations and prioritizes intellectual events over social commitments. He previously stood Auden up for their prom to attend an ecology conference.

Laura is Hollis's girlfriend, a graduate student studying science. She possesses a formal, analytical demeanor and straight posture that closely mirrors Victoria's personality. She is highly educated and tends to treat casual environments with academic seriousness.

Finn is one of Victoria's graduate students. He is deeply infatuated with his professor and desires a serious relationship, persisting in his affections despite Victoria's preference for casual arrangements.

Abe was Eli's lifelong best friend and fellow BMX biker who died in a car accident the previous year. Though he does not appear in the present narrative, his absence heavily influences the local friend group and serves as the source of Eli's grief and withdrawal.

Karen is Eli and Jake's mother. As a former maternity nurse who raised four children, she is highly capable and soothing in high-stress situations involving infants.

Belissa is Eli's ex-girlfriend who remains possessive of him after their breakup. She hosts local parties and is quick to show hostility toward any new girls who interact with Eli.