Sissy's role in the novel symbolizes the system of values that the book espouses. Despite her tendency toward promiscuity, Sissy remains steadfastly understanding and loving to every person who knows her. The way other characters view her demonstrates the novel's resistance to a conventional way of judging her. She is a well-loved character, despite her reputation with men. Her sisters cannot help but forgive her blunders and sexual exploits, and Francie adores her. The author suggests that her weakness with men is actually a result of her loving personality—she wants to give as much as she can, whether it is to a lover or her family. The novel holds her up as an example of a "good" person; it resists condemning her as the result of one weakness. In fact, the religious themes in the novel also point toward this idea; Katie thinks at one point that God will have to take into account Sissy's goodness when Sissy's soul is wandering through purgatory. This book, through Sissy, is challenging a traditional religious idea of judgment. It is also subtly suggesting that one think of women's sexuality in a more tolerant way.

Sissy and Johnny are similar characters in many ways: both have a weakness, and both have extraordinary qualities that redeem them. Although Sissy is one of the most dynamic characters in the book—changing from a promiscuous woman to a stable mother and wife—the reader should not view this change as a moralizing process. That is, the novel does not value one version of Sissy over the other. Her own desire for a child drives her ultimately to a more stable relationship, but the novel does not seek to correct or moralize her character. Francie, who as the protagonist oftentimes defines the values of the book, actually misses the old Sissy—the one who wore perfume, and had a beautiful, thin figure to attract men. Like Johnny, Sissy's fault is just that—a fault. It does not pervade her whole character. Francie loves both Johnny and Sissy passionately; this, too, is a testament to their goodness.