If this question is about Nick Carraway, the narrator of The Great Gatsby, then it goes without saying he is the most famous literary narrator named Nick in the world of English-language literature. The novel's first person perspective allows Nick to relate a fair amount of personal information. We learn fairly quickly that he is originally from the Midwest, that his ancestors avoided fighting in the Civil War by paying a surrogate to fight in their place while they worked in business, and that his family has only been in the country since 1851. This family background denotes ambition and a slight ruthlessness, and Nick himself heads East after the war to seek his fortune and escape the monotony of his hometown.
This ambition and ruthlessness characterizes Nick's willingness to socialize with the people surrounding Jay Gatsby, whose grand home is next to where he lives (in a small rented caretakers' cottage). Although he is somewhat reluctant to engage socially and somewhat shy at first, Nick allows Gatsby's crowd to turn his head and quickly becomes involved with the decadent party scene at Gatsby's mansion. It takes a while before he realizes that Gatsby's friends and Gatsby himself are cruel, shallow and manipulative people, suggesting his own sense of integrity is not as fundamental or ingrained as he might wish readers to believe.
Nick's narration is also fraught with inconsistency, especially where Gatsby is concerned; he moves from cautious suspicion, to willing hero worship, to aloof judgment, all in the space of a few weeks. It is almost as if the narrative voice in the novel, the persona of Mick Carraway, is desperately seeking the same sort of approval from readers that Gatsby is seeking from Nick.