Percy is a 30-year-old editor living in Toronto who struggles with anxiety and feels disconnected from her city life. At age 13, she begins spending her summers at her parents' cottage in Barry's Bay, where she develops a deep affinity for long-distance swimming, horror movies, and making woven friendship bracelets. She harbors a profound, enduring connection to her childhood best friend, carrying unresolved emotional weight from a sudden separation in their past.

Sam is a smart, academically driven young man who aspires to become a cardiologist following the sudden death of his father. As an adult, he works as a doctor and lives back in Barry's Bay to care for his family's property. He is naturally reserved and sometimes struggles to communicate his feelings directly, preferring to show his affection through quiet attention to details and shared activities.

Charlie is Sam’s older brother, known for his handsome, charming, and outgoing personality. He works in finance on Bay Street in Toronto. Growing up, he frequently flirts with Percy and likes to tease his younger brother. Beneath his frivolous exterior, he possesses a genuine, observant empathy and a protective instinct toward his family.

Delilah is Percy’s childhood friend from the city. She is popular and pretty, and she becomes fiercely protective of Percy once they overcome an early rift in their friendship. She is confident and ambitious, eventually attending the same university as Sam.

Chantal is Percy’s closest friend in adulthood. She is highly perceptive, encouraging Percy to attend therapy to manage her anxiety. Although Percy keeps parts of her past hidden, Chantal recognizes when her friend is hurting and offers unwavering emotional support.

Sue is Sam and Charlie’s mother, who runs the Tavern, a local restaurant serving Polish food. She is a warm, welcoming presence in Barry's Bay who treats Percy like family. Her funeral in the present timeline is the event that brings Percy back to the lake.

Buckley Mason, universally called Mason, is Delilah’s cousin and Percy’s first official teenage boyfriend. He is confident and attends the University of Toronto. His relationship with Percy introduces tension into her friendship with Sam.

Taylor is an elegant blonde woman who dates adult Sam. She meets him at a bar in the city and has an on-and-off relationship with him, bringing a new dynamic to Percy and Sam's reunion in Barry's Bay.

Sebastian is Percy’s most recent boyfriend in the city. They date for seven months, making it Percy's longest adult relationship, but she breaks up with him because she lacks a deep emotional attachment to him.

Julien is the dedicated chef at the Tavern who works closely with the Florek family. He is a steady fixture in the local Barry's Bay community and eventually takes on a larger role at the restaurant.

Patel is Mason's best friend and Delilah's teenage boyfriend. He frequently joins group outings and double dates during the summer holidays at the lake.

Jordie is one of Sam's close friends from Barry's Bay who attends the same university. He is highly protective of Sam's emotional well-being and skeptical of past relationships resurfacing.

Finn is another of Sam's local friends from Barry's Bay. Like Jordie, he is fiercely loyal to Sam and openly voices his concerns about anything that might cause his friend pain.

Ms. George is Percy's strict but beloved ninth-grade English teacher. She recognizes Percy's talent for creative writing and encourages her to enter a short-story competition.

Percy's mother is a professor at the University of Toronto. She supports buying the lakeside cottage to help her daughter recover from school bullying and encourages Percy's independence.

Percy's father is a university professor who supports purchasing the Barry's Bay cottage. He encourages Percy to befriend the local boys, recognizing that his daughter needs companionship.

Maeve is a girl from Barry's Bay whom teenage Sam kisses. This event prompts early feelings of jealousy in Percy.

Anita is Charlie's older girlfriend during the summer Percy turns 16. She accompanies him on group outings to the lake and observes the younger friends' dynamics.