Madeleine is a seventeen-year-old from a wealthy New York family. She possesses a firm understanding of her own mind but feels overwhelmed by the intense public attention her courtship attracts. She prefers outdoor activities over high society's rigid customs. She values authentic emotional connections rather than adhering to the expectations of the established elite.

Jack is a forty-six-year-old colonel and heir to one of America's largest fortunes. Following a scandalous divorce, his interest in the much younger Madeleine creates intense tabloid fodder. He is worldly and confident. He expects the privileges his famous name brings and handles public scrutiny with practiced ease.

Vincent is the eighteen-year-old son of Jack and Ava. He struggles with the fallout of his parents' highly public divorce. He carries a brooding demeanor and frequently directs his anger at those entering his father's life.

Margaret is an older society matron originally from Denver. Having experienced rejection from the elite circles in her own hometown, she ignores New York's strict class rules. She acts as a mentor to Madeleine as the younger woman enters the Astor world.

Katherine is Madeleine's older sister. She is a popular and admired young woman in Bar Harbor's summer society. She understands the expectations of their class but encourages her sister to prioritize genuine affection over superficial matches.

William is a successful New York shipping businessman. He built his family's wealth through industry rather than inheriting old money. He cares deeply for his daughters' happiness and offers a steady, grounding perspective.

Mrs. Force is a socially conscious mother who manages her family's summer schedule and social obligations. She understands the unspoken rules of the Gilded Age elite. She tries to prepare Madeleine for the harsh realities of public life.

Ava is a Philadelphia socialite and Jack's former wife. Her divorce from Jack created a massive scandal among the Four Hundred. Though physically absent from the early narrative, her legacy sets an intimidating standard for the Astor household.

Caroline, known simply as the Mrs. Astor, is Jack's mother. She historically ruled New York's elite Knickerbocker society, deciding who belonged in the exclusive Four Hundred. Her standards and judgments still echo through her family's properties.

Alice is the eight-year-old daughter of Jack and Ava. She lives in the shadow of her parents' highly publicized divorce and her father's new courtship.

Kitty is Jack's large, energetic dog. She travels extensively with him, bypassing strict rules that typically forbid animals in elite spaces. She brings out a relaxed, informal side of her owner.

Jakey is Madeleine's son. He serves as the primary audience for the narrative, as his mother records the details of her courtship and marriage so he will understand his family's history.

Mrs. Cardeza is a wealthy, established society matron. She embodies the snobbery of the old-money Knickerbockers who view Jack's new relationship as inappropriate and scandalous.

Carrie is a professional nurse. Jack employs her to monitor Madeleine's health during her pregnancy. Her presence reflects his protective nature and immense financial resources.

J. Bruce Ismay is the chairman of the White Star Line. He boasts to Jack about the magnificent new ship he is building. He is focused on setting speed records and showcasing his company's maritime achievements.

Helen is Margaret Brown's daughter. She accompanies her mother and the Astors on parts of their international travels.