Nick Carraway is a confidant to both Jay Gatsby and Daisy Buchanan. He is the catalyst for the telling of The Great Gatsby.
Previous to Nick's arrival, there are two Eggs. West Egg, which houses Jay Gatsby and the "new money", and East Egg, which is where Daisy Buchanan and the "old money" live. Nick comes to town as a sort of mediator who doesn't have much money so he's not affiliated with East or West. His mediator role is strengthened, too, by the fact that he's acquainted with people on both Eggs.
Nick soon meets Gatsby and they don't click right away, but Gatsby's charm takes him in. Daisy is Nick's cousin so she trusts him. Both Daisy and Gatsby confide in Nick, which sets the scene for their meeting. Gatsby uses the term "old sport" to show his affection, while Daisy is constantly hugging and chatting and the like. Daisy talks to Nick about her kid and Jordan while Gatsby talks mainly about Daisy. When the meeting finally comes, it's Nick who leads Daisy to Gatsby because he couldn't meet her alone.The reason The Great Gatsby is centered on Nick is because he is the link between east and West. His character doesn't do much, but things happen near him a lot so is the perfect objective storyteller. By placing him as a confidant, Fitzgerald achieved a way to relay an almost unbiased story. As a confidant, Nick allows us to see into the deepest parts of Gatsby and Daisy. Gatsby lays out his entire life story, eventually, and proves that he's a good guy after all. Daisy wears her thoughts on her sleeve more, but at the end Nick exposes her and the rest of the East Eggers as the ignorant, self-serving hippocrites they really are.
By making Nick nearly neutral, we were able to see the story of a summer conflict unfold from both sides.
