A major concern of Oliver Twist is the question of whether a bad environment can irrevocably poison someone’s character and soul. As the novel progresses, the character who best illustrates the contradictory issues brought up by that question is Nancy. As a child of the streets, Nancy has been a thief and drinks to excess. The narrator’s reference to her “free and agreeable . . . manners” indicates that she is a prostitute. She is immersed in the vices condemned by her society, but she also commits perhaps the most noble act in the novel when she sacrifices her own life in order to protect Oliver. Nancy’s moral complexity is unique among the major characters in Oliver Twist. The novel is full of characters who are all good and can barely comprehend evil, such as Oliver, Rose, and Brownlow; and characters who are all evil and can barely comprehend good, such as Fagin, Sikes, and Monks. Only Nancy comprehends and is capable of both good and evil. Her ultimate choice to do good at a great personal cost is a strong argument in favor of the incorruptibility of basic goodness, no matter how many environmental obstacles it may face.
Nancy’s love for Sikes exemplifies the moral ambiguity of her character. As she herself points out to Rose, devotion to a man can be “a comfort and a pride” under the right circumstances. But for Nancy, such devotion is “a new means of violence and suffering”—indeed, her relationship with Sikes leads her to criminal acts for his sake and eventually to her own demise. The same behavior, in different circumstances, can have very different consequences and moral significance. In much of Oliver Twist, morality and nobility are black-and-white issues, but Nancy’s character suggests that the boundary between virtue and vice is not always clearly drawn.