Lily is a 23-year-old college graduate who relocates to Boston seeking a fresh start. She uses her inheritance to open an unconventional flower shop, channeling her lifelong passion for gardening into a career. She carries complicated feelings about her childhood and her parents' marriage, prompting her to process her past by reading her old teenage diaries addressed to Ellen DeGeneres.

Ryle is a confident, handsome resident neurosurgeon living in Boston. Highly focused on his demanding medical career, he initially professes zero interest in serious commitments, preferring brief and casual encounters. He pursues Lily persistently, challenging her boundaries while remaining heavily guarded about his own family history.

Atlas is a young man who forms a critical bond with Lily during their teenage years in Maine. Cast out of his home with no resources, he relies on Lily's assistance to survive the winter while aiming to finish school and join the military. He shares a quiet understanding of difficult home lives with Lily, creating a lasting imprint on her life.

Andrew is the recently deceased former mayor of Plethora, Maine, and Lily's father. Highly conscious of his public image, he presented a respectable facade to the town while maintaining a volatile household behind closed doors. His actions heavily influence his daughter's views on love and personal boundaries.

Jenny is a former teaching assistant and Lily's mother. She spent years caring for her husband and enduring a difficult marriage in Maine. Following his death, she attempts to support her daughter's move to Boston while managing her own complicated grief and finding her footing in a newly independent life.

Allysa is an effervescent, wealthy young woman who becomes Lily's first employee and closest friend in Boston. She offers to work for free simply to keep herself busy and distracted from her personal struggles. She provides enthusiastic support for Lily's entrepreneurial vision and serves as a loyal confidant.

Marshall is Allysa's husband and Ryle's brother-in-law. He is a supportive partner who frequently socializes with Allysa and Ryle in Boston, providing a steady and agreeable presence in their lively social circle.

Emerson is Ryle and Allysa's older brother who passed away when they were children. His death deeply impacted the Kincaid family, shaping Ryle's psychological development and lingering as a highly sensitive topic among the surviving siblings.