Henry is a middle-aged, expatriate American writer who lives in England and identifies as a cosmopolitan citizen of the world. He prefers solitude to the demanding social obligations of his affluent circles, using his careful observations of friends to fuel his psychologically accurate novels. He hides his romantic attraction to men, viewing societal discretion as a necessary survival tactic.

Lady Wolseley is a prominent socialite married to a high-ranking military officer. She thrives on attending elaborate balls and maintaining strict class divisions within her wealthy social circles. She frequently assists Henry with practical matters, such as furnishing his home, and subtly supports his need for discretion regarding his private life.

William is Henry's elder brother, a decisive academic who pursues a career in psychology and philosophy. He shares his family's travel-heavy, cosmopolitan upbringing but maintains a more direct and assertive approach to life. The two brothers frequently disagree over family matters but ultimately recognize their shared values.

Alice is Henry and William's younger sister. She experiences intense social anxiety and severe depression, eventually receiving a diagnosis of "hysteria" from nineteenth-century doctors. She shares a sympathetic bond with Henry due to their mutual difficulties fitting into conventional society, eventually becoming bedridden as her physical and emotional health declines.

Corporal Hammond is an Irish-born man raised in London who previously served as a soldier under Lord Wolseley. He speaks with a quiet discretion and maintains a calm, dignified presence. He initiates a cautious flirtation with Henry during the visit, offering a brief possibility for intimacy that remains unfulfilled.

Oscar Wilde is a highly popular, financially successful playwright whose broad public appeal sharply contrasts with Henry's niche intellectual audience. He lives openly as a gay man and flaunts his affluent lifestyle. His public trials for indecency serve as a warning to Henry about the dangers of living authentically.

Oliver Wendell Holmes Jr. is an outgoing, adventurous old friend of Henry's who enjoys spirited conversations. He maintains a respectable public persona but enjoys risqué discussions in private. He harbors resentment toward Henry regarding the care of their mutual friend Minny Temple during her final year.

Minny is Henry's vivacious, orphaned cousin. She maintains an independent spirit that heavily influences Henry's creative output. Her premature death affects Henry profoundly, prompting him to immortalize her personality in several of his fictional protagonists.

Constance is a sensitive, intellectual writer and the grand-niece of James Fenimore Cooper. She shares Henry's introversion, artistic sensibilities, and transient lifestyle across European cities. She battles severe winter depression and relies on correspondence with her tight-knit circle of friends.

Hendrik is a talented and ambitious sculptor whose work garners significant praise among European social circles. Raised in Newport, Rhode Island, he shares Henry's background but possesses a vitality and physical presence that the older writer finds highly attractive.

Henry Senior is a wealthy public intellectual and philosopher. He moves his family across Europe to instill a worldly perspective in his children, though he openly favors his more decisive, academic sons over those who struggle in school.

Wilky is one of Henry's younger brothers. He joins the Union army during the American Civil War, serving alongside Black soldiers, and sustains severe injuries in battle that cause him lasting physical pain.

Bob is another of Henry's brothers who lacks interest in scholarly pursuits. Like Wilky, he enlists in the Union army during the Civil War, remaining with his regiment throughout the conflict.

Lily is a polite, well-mannered friend of Henry and Constance. She visits Henry following Constance's death and directly accuses him of failing to provide adequate emotional support to their mutual friend.

Mrs. Smith manages the kitchen staff at Henry's estate. Over time, she develops a severe alcohol addiction, becoming belligerent toward Henry and increasingly incapable of preparing meals for his guests.

Mr. Smith is a servant in Henry's home who begins drinking heavily. His intoxication makes him unable to properly serve food during formal dinners, causing Henry intense embarrassment in front of guests.

Peggy is William's daughter and Henry's niece. She is an avid reader who eagerly discusses literature and the writing process with her uncle during her stay at his home.

Alice is William's wife, a practical woman who closely monitors her husband's declining health. She travels with him to London to seek specialized medical treatment for his heart condition.