These characters each play a very significant role in shaping Jay Gatsby's character and his destiny. Dan Cody comes into Gatsby's life first, while Gatsby is still known as Jimmy Gatz from North Dakota. When he first sees Dan Cody's beautiful yacht and meets Cody himself, Jimmy becomes Jay Gatsby, the romantic vision of himself he has harbored all his life. A millionaire many times over, Cody employs Gatsby on the yacht, dresses him well, and takes him around the continent three times, into a rich life he had never known. Because Cody drinks, Gatsby learns not to drink. When Cody dies, Gatsby is cheated out of an inheritance. He walks away penniless, but he had lived his dream for a little while. He wants more.
Coming home from World War I, Gatsby is broke, owning only the clothes on his back, his uniform. He is hungry, literally, when he meets Wolfsheim in a pool hall. Wolfsheim is a gangster. He puts Gatsby to work in his criminal activities. Gatsby becomes enormously rich very quickly, but his life is not respectable. He becomes corrupt through his association with Wolfsheim.
Now having money, Gatsby tries to repeat the past by winning Daisy back. Since loving and losing her before going to war, Gatsby has been obsessed with her. She has become his dream. Their reunion and the continuation of their affair leads directly to his death. Daisy shapes his destiny by twice drawing him into a relationship that could never survive the difference in their social classes.