Jurgis bumps into Freddie Jones one cold night as he is begging. Freddie is the son of one of the meatpacking plant owners. He is drunk off his head, but he is also very sweet. He invites Jurgis home with him to have dinner when Jurgis explains that he is cold and hungry. When Jurgis sees inside of the Jones family mansion, he realizes that he has never seen so much wealth in one place in his life before.
Although Freddie Jones seems well set up in this life, Sinclair makes a point to show that even Freddie is not free from the terrible influence of business on personal relationships. His father is distant and controlling with Freddie and his siblings. Freddie is also totally dependent on his father to support his wasteful, pointless lifestyle. So Freddie has no freedom. His giant mansion is like a cage, and Jones Sr. pays his servants to monitor Freddie's behavior in his absence. As usual in this novel, money stifles and ruins personal relationships.
On a plot level, Freddie Jones is also important because he provides the pretext to get Jurgis in jail a second time. In Freddie's drunken haze, he gives Jurgis a hundred dollar bill. Jurgis is strongly tempted to steal the rest of Freddie's cash (because he could obviously use it a lot more than Freddie can). Jurgis, however, never really gets up the nerve. So instead, after Hamilton the butler boots Jurgis out of the Jones family mansion, Jurgis immediately takes this hundred dollar bill to get change at a local bar. The bartender steals Jurgis's cash (of course) and Jurgis attacks him. Because the judge cannot believe that Jurgis is telling the truth about having a hundred dollars in the first place (because he looks homeless), Jurgis gets thrown in jail for ten days. So Jurgis happens to meet Jack Duane a second time and fall into a life of crime, and it's all thanks to drunken Freddie Jones and his hundred dollars.