Charlie is a family lawyer in her late twenties living in New York City. She co-owns the firm Mason and Romano with her best friend and owns her own Manhattan apartment. Nine years prior to the current events, she suffered a severe mental breakdown following the end of a secret relationship with an older married man. She actively works to maintain a healthy, stable lifestyle and tries to focus on her career and her promising new dating life, though the sudden reappearance of her former lover threatens her carefully built stability.

Lex is the wealthy, mid-thirties head of a real estate and nightclub investment business called the Lexed Group. During his time in medical school a decade ago, he went by the name Alex. Following a devastating breakup, he abandoned medicine to become a steely, austere businessman who divides his time between London and New York. He maintains a highly controlled exterior that quickly falters when he is confronted with his past.

Julian is a journalist who lives in New York and frequently travels to Washington, D.C., for assignments. He quickly falls for Charlie after their gym encounter and offers her a stable, passionate partnership. He is eager to build a traditional life, including marriage and children, but he occasionally exhibits frustration regarding Charlie's unresolved past.

Nikki is Charlie's best friend from their time at Yale Law School and her partner at Mason and Romano. She balances her demanding career with a busy family life alongside her husband and young son. She provides a grounded perspective for Charlie, urging her to confront her lingering feelings before entering a new marriage.

Adriana is Lex's younger sister and Charlie's former childhood best friend. She severed ties with Charlie years ago after discovering the secret romance between Charlie and her married brother. Now engaged to be married herself, Adriana seeks to make amends with Charlie and repair their broken friendship.

Samantha is Lex's ex-wife, whom he met and married during their college years. During their marriage, she frequently clashed with him over her desire to have children while he attended medical school. Years later, she expresses regret for her past behaviors and the resulting complications she caused in Lex and Charlie's lives.

Kate is a British woman who works as Lex's assistant at the Lexed Group. She is highly perceptive regarding her boss's intense moods and workaholic tendencies. She strikes up a chance friendship with Charlie while jogging in New York, initially unaware of Charlie's deep history with her employer.

Rocky is Nikki's husband and the father of their seven-year-old son, Will. He is a supportive, constant presence in Nikki's life and regularly participates in group outings, game nights, and trips to the Hamptons with Charlie and their extended friend circle.

Will is the seven-year-old son of Nikki and Rocky Romano. He is deeply fond of Charlie, who considers him an important part of her chosen family. He playfully observes the romantic dynamics among the adults in his life and voices his own opinions on their relationships.

Eric is Charlie's assistant at her law firm. He operates as both a professional aide and a protective friend, frequently accompanying Charlie to social events like charity balls and intervening when personal tensions escalate in public spaces.

Finn is Charlie's ex-boyfriend and her first sexual partner from her teenage years. He remains a close friend into their adulthood, actively encouraging her to let go of her past heartbreak and embrace her new life with Julian.

Elijah is Adriana's fiancé. He is thoroughly integrated into her social circle and participates in group gatherings, including trips to the Hamptons and Charlie's birthday celebrations.

Victoria is the executive director of Preston Enterprises, a major client of the Lexed Group. Based in London, she holds significant professional leverage over Lex and openly expresses her romantic interest in him during their business dealings.

Emma is Nikki Romano's assistant at the law firm. She is part of the close-knit office environment and frequently joins the broader social gatherings to celebrate Charlie and Nikki's personal milestones.

Bryce is an investigator or information broker employed by Lex. He uncovers details about Charlie's education, career, relationship status, and past medical history at Lex's request.

Carter is a classmate from Charlie's high school days who behaves aggressively toward her. He later takes her to the prom, sparking intense jealousy and violent protective instincts from Lex.

Brooke is a woman Adriana sets up to attend a charity ball with Lex. She openly admits her romantic preference for women but agrees to help Lex by acting as his date to make his ex jealous.