The NPD (narcissistic personality disorder) businessperson is acutely aware of who is getting what in terms of recognition, opportunity, and power-making decisions. The ability to gain influence over potential competitors is a drive that will not abate until the NPD individual has surpassed that person or neutralized any threat to his own goal. Consequently, you must achieve a bottom line of boundary setting ability with this person. This is essential if you are going to prevent problems or defend yourself effectively from the NPD coworker or, worse yet, the NPD boss. Along with protecting yourself from hurt, exploitation, or betrayal, we are also now talking about self-preservation in terms of your career.
-- Eleanor D. Payson, The Wizard of Oz and Other Narcissists, p. 146