Sophia Western, according to critic Martin Battestin, is an allegorical figure, meant to represent the feminine ideal and therefore kept as anonymous as possible. For example, the narrator does not provide concrete details of Sophia's appearance and character when he introduces her at the beginning of the novel, and by the end of the novel, we do not know much more. Although Sophia's decision to run away from her violent father Squire Western signals her courage and bravery—which the narrator says is becoming in a woman—she actually does very little in the novel. As a woman and obedient daughter, Sophia must allow herself to be acted upon, and even though she falls in love with Tom Jones before he falls in love with her, she cannot, in all decency, say anything. Similarly, Sophia puts up little resistance to her father's violence toward her.

Sophia becomes the spokeswoman for male chastity at the end of the novel—ironically, through her lecture to Jones, she provides the final obstacle to their marriage and thus to the fulfillment of the comic plot. Through her generosity and genuine courtesy, Sophia becomes a representative, along with Jones and Allworthy of Fielding's vision of Virtue. She combines the best of the country and the city, since she has manners, unlike her country father, but they are genuine, unlike those of her courtly aunt, Mrs. Western. Similarly, Sophia combines the merits of the novel's two other heroes without any of their faults—she is kind like Tom, but also remains chaste, and is generous toward others, like Allworthy, without being blind to their faults.