From Discworld & Terry Pratchett Wiki
The New Firm is devoted to making things happen, by any means at all, no matter how little those things want to happen, and they are very successful. This kind of service commands very high fees, payable in precious stones, from a certain class of businessmen and politicians. The New Firm consists of Mr. Tulip and Mr. Pin. Mr. Pin is small and slight with a rather large head which contains the brains of the organization. Mr. Tulip provides the muscle, the threat, and the execution (actually quite a number of executions). Mr. Pin would kill anyone, too, but he would calculate the risk and benefits and expect to profit from it. He has no desire for violence, just its monetary rewards. He is quite careful of his health and appearance and considers that his only vice is smoking. Mr. Pin comes to an unfortunate end in The Truth.
He is an utterly despicable character and will even stoop so low as to steal somebody's Potato.
Bears a striking resemblance to Mr. Croup from Neil Gaiman's Neverwhere, who, along with his partner Mr. Vandemar (similar in many respects to Mr. Tulip) forms part of the Old Firm. However, TP has stated that rather than being a direct parody, the New Firm are an amalgam of all two-man crime teams from everywhere and everywhen in fiction.