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.