Bertha is a 30-year-old affluent wife and mother living in London during the early 1900s. She enjoys a comfortable, modern lifestyle filled with servants, artists, and dinner parties, but she struggles to process sudden, overwhelming feelings of bliss. She perceives herself as having a perfect life and often suppresses her deeper emotions to conform to the polite expectations of her social class.

Harry is Bertha's husband, a man who loves operating at high pressure and makes a point of entering rooms with extravagant coolness. He maintains a brusque, sometimes insulting frankness that Bertha interprets as an endearing idiosyncrasy. He acts as a polite but distant companion to his wife in their platonic marriage while confidently moving through their affluent social circles.

Pearl is a pale, quiet woman whom Bertha recently met at a club and eagerly invited to dinner. She moves with a still, sleepy grace and rarely makes direct eye contact, maintaining a strange half-smile. She represents the thrilling type of modern friend Bertha cultivates, exuding an enigmatic aura that deeply fascinates her host.

Mrs. Norman Knight is an energetic, eccentric woman deeply interested in interior decoration. She shares a close, almost singular identity with her husband, and she openly mocks the conservatism of middle-class society. Her lively, somewhat theatrical nature contrasts sharply with the stillness of the other female guests.

Mr. Norman Knight is a respectable, theater-loving man who hopes to start a venue for unwritten plays. He projects a polite, slightly chivalric demeanor while sharing a tightly bonded, affectionately mocking relationship with his wife. He enjoys performing for his friends and uses his monocle for dramatic effect during his anecdotes.

Eddie is a lean, pale young poet who recently published a small book of poetry. He speaks in a highly affected, melodramatic manner, often emphasizing arbitrary words to heighten the drama of mundane events. He fits perfectly into the Youngs' circle of artistic friends.

Nanny is the traditional caretaker employed by the Youngs to raise their daughter. She establishes clear dominance in the nursery, expecting deference from her employers regarding the baby's routine. She feels easily offended when her control over the child is interrupted or challenged by Bertha.

Little B is the infant daughter of Harry and Bertha Young. She is an adorable, well-cared-for baby who spends the vast majority of her time with her nanny, following a strict upper-middle-class routine.

Mary is the housemaid employed by the Youngs. She manages the practical, day-to-day operations of the house, such as receiving deliveries and ensuring the residence is prepared for the family and their dinner guests.