Nick, Jordan, Tom, and Daisy come from the same social set. Daisy and Nick are cousins while Tom and Nick are college friends. Jordan and Daisy are girlhood friends. Tom and Daisy have heard rumors from others in their set that Nick is engaged, although this is not true. Most significantly, snobbish Tom accepts Jordan and Nick as social equals and fellow "Nordics."
Tom and Daisy, however, are vastly wealthy, with polo ponies and a mansion, while Nick and Jordan depend on the largesse of relatives. Nick is being bankrolled by his father to start a career in finance, and Jordan lives with an aged relative in New York City. Nick rents a modest home next to Gatsby's mansion and goes to work in New York City everyday on the train.
Nick and Jordan show that acceptance into Tom and Daisy's social set is a function of class—education and background—rather than wealth. They are "in," while the wealthy Gatsby is too nouveau riche for acceptance, at least in the eyes of Tom.
Nick is ever-steady, the observer, the person people can confide in. Jordan is impressively cool and unflappable. Tom is a brutal buzzkill, the type who can ruin any gathering, while Daisy is a charismatic drama queen, always charming but never reliable.