Iona is a 57-year-old advice columnist for a women's magazine who maintains a strict daily routine on her commute. A former socialite and dancer from the 1980s and 90s, she projects an intimidating, glamorous facade but privately worries about remaining relevant in a youth-obsessed industry. She is deeply devoted to her partner, Bea, and naturally drawn to solving the problems of the strangers around her.

Piers is a 38-year-old futures trader known among his peers as "Midas" for his financial success. He lives in a Surbiton mansion and projects the image of a wealthy, accomplished businessman to the other passengers on the train. Beneath his prosperous exterior, he harbors deep unhappiness with his high-pressure career and the materialistic lifestyle he feels forced to maintain.

Sanjay is a young oncology nurse in his twenties who commutes from New Malden. He is highly empathetic and dedicated to his patients, though his intense compassion often triggers anxiety and panic attacks about his professional competence. He is observant, tender-hearted, and nursing a quiet crush on a fellow passenger.

Emmie is a young woman in her twenties with red hair who works in an advertising firm. Despite her early ambitions of saving the world, she finds herself uncomfortable with the ethics of her industry, specifically ad campaigns targeting young women's self-esteem. She is romantic and imaginative, though she privately deals with unsettling text messages from an anonymous sender.

Martha is a Year 10 high school student trying to understand the complicated social hierarchies of her peers. She feels isolated and faces intense bullying at school after a private photo she sent to a classmate circulates among her class. Despite her fears, she is resilient and seeks guidance from the older adults on her commute to help build her confidence.

Bea is Iona's partner of 35 years and a former dancer. A striking Black woman who shares Iona's history in the 1980s socialite scene, she has always been a fierce advocate for living openly and unapologetically. She currently resides in a care home due to early-onset Alzheimer's, remaining the foundational love of Iona's life.

David is an older lawyer who has been taking the commuter train for decades. He presents as a conventional, routine-driven professional but is privately reeling from sudden and severe marital distress. He finds himself unexpectedly unburdening his personal problems to his fellow commuters.

Candida is Piers's wife, accustomed to a luxurious lifestyle in their Surbiton mansion. She prioritizes their high social status and material comfort, heavily relying on Piers's substantial income to maintain the household and employ staff like their au pair.

Toby is Emmie's boyfriend who works at a tech company. He is highly attentive to Emmie, frequently cooking for her and encouraging her to work from home. He projects the image of an ideal, protective partner, though his intense focus on her routines begins to feel restrictive to Emmie.

Ed is the younger editor at the women's magazine where Iona works. He relies heavily on corporate jargon and beanbag brainstorming sessions. He views Iona as outdated and constantly pushes her to make her column more appealing to a younger demographic.

Jake is a muscular personal trainer who owns a gym. He is a regular on the commuter train who gets drawn into Iona's orbit, offering practical support and self-defense advice to the younger commuters.

Fizz is a young TikTok sensation and social media influencer. Despite her youth and modern platform, she has a deep admiration for the older generation of influencers and is eager to connect with seasoned figures in the industry.

Julie is an oncology patient undergoing difficult treatments for cancer. She experiences the physical and emotional tolls of chemotherapy, relying on the medical staff for comfort and reassurance during her scary hospital visits.