Bankers regularly make promises to clients that run afoul of their credit committees, but former GE Chairman and CEO Jack Welch believes Lee is especially adept at navigating this territory. "He knows how much running space he's got," says Welch, who calls Lee, "the most incredible client person that anybody ever had." In addition to his dedication to his clients, Lee also has great technical skills, according to Chris Flowers, the longtime Goldman Sachs ( GS) banker who is now head of financial services-focused private equity firm J.C. Flowers & Co. "He knows all the products really well," Flowers says. Lee also knows how to get fees on those products, earning him the nickname, "Jimmy Fee." One corporate executive told TheStreet.com that he wanted a lower fee from JPMorgan and went to Lee citing the views of two more junior bankers that it should be reduced. Lee responded that he didn't care what the junior bankers thought any more than he cared what his two secretaries or his driver thought, as he was the vice chairman of JPMorgan. Lee's success has made him accustomed to getting his way, a trait that extends beyond his business dealings to things like his own golf score, according to several sources. His liberal scorekeeping apparently led to an interesting game with New York Mayor Michael Bloomberg, who has a reputation for scrupulous adherence to the rules, according to one private equity executive. "We have nothing to add," said a spokesman for the mayor who was asked to confirm this report.