Nancy is the youngest of Herb and Bonnie Clutter. Nancy's known as the Town Sweetheart, and in the fifties this was an okay thing to call a girl. She runs her busy schedule with the efficiency of a drill sergeant, but without the screaming. Nancy seems to delight in charming everyone, even confronting the men with guns in the middle of the night with what they're doing, with a big smile. She's used to being able to win people over. She's a brave kid: she talks with Perry for a while the night of the murders, "trying hard to act casual and friendly." (3.477)
Nancy and Bobby Rupp have been dating steadily since the sixth grade. She loves Bobby, but knows that her father doesn't want her to marry him, because Bobby's a Roman Catholic and she and her family are Methodists. Her father requested that she go out less often with Bobby, and so far it hasn't worked. We know though, that as a dutiful daughter, she would probably have eventually acquiesced.
Nancy's one of those amazing young women who finds time for everything:
Where she found the time, and still managed to "practically run that big house" and be a straight-A student, the president of her class, a leader in the 4-H program and the Young Methodists league, a skilled rider, an excellent musician (piano, clarinet), an annual winner at the county fair (pastry, preserves, needlework, flower arrangement)—how a girl not yet seventeen could haul such a wagonload, and do so without "brag," with rather, merely a radiant jauntiness, was an enigma the community pondered, and solved by saying, "She's got character. Gets it from her old man." (1.32)
Nancy's all-around awesomeness is in stark contrast to her depressed, poorly-functioning mother. We think this description has its intended effect on the reader—to see the lost potential of Nancy's young life.
But she's dead, too, by page 72, and we never get to see what might have happened as she got older—would she sneak cigarettes and beer? Go to third base with Bobby? Drop out of college? She's frozen in time as the dutiful, delightful daughter.