Arabella is a 17-year-old woman raised in isolation on a country estate. She possesses great intelligence and beauty but views the world entirely through the lens of French romance novels. She assumes her life will mirror the epic adventures, duels, and grand declarations of love found in her books. This framework dictates her unusual behavior and causes frequent misunderstandings with the people around her.

Mr. Glanville is Arabella’s cousin and the man her father intends for her to marry. He is a practical and sensible English gentleman who lacks the romantic disposition Arabella expects. He falls in love with her despite her eccentricities and struggles to comprehend her elaborate rules of courtship.

Sir George is a neighbor and acquaintance of the Glanville family who pursues Arabella's affection. He possesses a shallow knowledge of French romance novels and uses this information to endear himself to Arabella. He crafts elaborate stories to present himself as a heroic figure, though his actions expose him as a cynical manipulator.

Miss Glanville is Mr. Glanville’s sister and Arabella’s cousin. She is a fashionable woman who envies Arabella’s beauty and charm. She frequently tries to shame or embarrass Arabella in public settings but fails to understand Arabella's immunity to societal expectations. She harbors an affection for Sir George.

The Marquis is Arabella’s father, a former member of the Royal Court who lives in self-imposed exile in the countryside. He raises Arabella alone following his wife's death during childbirth. He attempts to protect his daughter but unintentionally fuels her delusions by granting her access to his extensive library of romances.

Sir Charles is the Marquis’s brother and the father of Mr. Glanville and Miss Glanville. Following the Marquis's passing, he assumes responsibility for Arabella's estate and guardianship. He wishes to see Arabella marry his son but remains thoroughly baffled by her eccentric worldview.

Lucy is Arabella’s loyal maid and closest confidant. She willingly accepts her mistress’s strange statements and fears, providing a credulous audience for Arabella's dramatic interpretations of everyday events. Her forgetfulness occasionally creates fresh misunderstandings.

Mr. Hervey is an early gentleman suitor of Arabella. He offends her with his lack of romantic sensibilities, leading her to demand his death or banishment in accordance with chivalric rules. He finds her behavior amusing and readily mocks her innocent beliefs.

Edward is a young, attractive, well-spoken gardener working on the Marquis's estate. Arabella convinces herself that he is a nobleman in disguise plotting to declare his love for her. This assumption leads to his unfair dismissal from his position.

Miss Groves is a young woman whom Arabella spots in a nearby village. Arabella attempts to befriend her, assuming she possesses an adventurous past. She quickly offends the woman with overly dramatic interpretations of her personal history.

Mrs. Morris is the servant of Miss Groves. She explains her employer's complicated and scandalous past to Arabella. Arabella immediately recasts the scandalous details as a grand romantic adventure.

Mr. Selvin is a man Arabella meets in Bath who possesses a reputation as a historian. His knowledge proves superficial when he cannot comprehend Arabella's references to historical romances. He admires her intellect and desires her approval despite his confusion.

Mr. Tinsel is a cynical gentleman in Bath who attempts to draw compliments from Arabella for his amusement. He quickly concludes she is a fool when she dismisses his scandalous stories and demands chivalric behavior.

The Countess is an esteemed woman Arabella encounters in Bath. Having read many French romances in her youth, she communicates with Arabella on her own terms. Their shared understanding of chivalric language forms a fast but short-lived friendship.

Cynecia is a young woman Arabella encounters crying in a park near London. She tells Arabella a dramatic story about fleeing her homeland and searching for an unfaithful lover. Her tale appeals directly to Arabella's romantic sensibilities.

The Doctor is a medical professional who treats Arabella after a harrowing incident in the river. He uses reason, logic, and respectful dialogue to engage with her ideas rather than mocking them.

Mr. Roberts is Mr. Glanville’s servant. He rescues Arabella from the River Thames when she leaps in to escape imaginary attackers.