Through Nick Carraway as the novel's narrator, Fitzgerald achieves numerous literary purposes. Here are a few of the most important ones:
1. In structuring the novel in Nick's retrospective point of view, mystery and suspense are created. Whatever happened in the summer of 1922 continues to haunt Nick and was responsible for his returning from the East, even though he had intended to stay and pursue a new career. Also, the mysteries of Gatsby's character are solved slowly throughout the novel; readers learn the truth about Gatsby as Nick uncovers it, one piece at a time.
2. Nick functions in the novel as an "outsider," a Midwesterner who finds himself living among the wealthy in a culture very foreign to him. He soon becomes drawn into the personal lives of Gatsby, Jordan, and the Buchanans. He is both observer and participant, but Nick does not lose his own identity, which is grounded in Midwestern values; instead he becomes a moral contrast to the others and the voice of morality in the novel.
3. The novel's major theme is developed through Nick. His ultimate contempt for Tom and Daisy and his going home to the Midwest express the novel's condemnation of the corruption of the American Dream as represented by the moral corruption of the Eastern establishment upper class.
4. Nick serves as a functional character in the plot, also. He serves as the means to bring Daisy and Gatsby together. He has a history with Daisy, he lives next door to Gatsby, and he falls into a relationship with Jordan Baker, Daisy's friend who was present during Daisy's love affair with Gatsby in Louisville. Fitzgerald positions Nick in these ways to arrange the reunion between Gatsby and Daisy and to become a party to their secret summer affair so that he can relate and interpret Gatsby's feelings for readers.
Nick Carraway tells the story but also plays a very significant role in it. He is a major character in developing the plot, structure, conflicts, contrasts, and themes in the novel.
One of the first things we learn about Nick is that he prides himself on his honesty. While Nick is not perfect, he does establish himself as a reliable narrator and probably the one character in this series of events who has a relatively balanced view of Gatsby. Nick finds faults with Gatsby’s dubious business dealings and the fact that his life is a lie. But he admires his self-reliance romantic idealism. Since Nick is the only one at Gatsby's funeral, he must have been one of Gatsby's closest friends. Who better to tell his story?
Also, Gatsby is mysterious. Using Nick as narrator adds to the suspense. If Gatsby had narrated the novel, he would not have been that mysterious. The story is about Gatsby; not by Gatsby. It is essentially a character study. If Gatsby had narrated, it would have been a fictional autobiography. Nick is integrally involved in the story, but his objectivity makes it seem like he’s outside the story looking in.