While an occasional passive-aggressive approach to life's problems isn't unusual, for some people manipulation and indirect communication are a way of life. Passive-aggressive people often go undetected in the office and in their social circles--at least initially--because they disguise their seething hostility with a pleasant demeanor.
When you're building a career, it's easy to get caught up in the corporate game. Each industry and company has its own flavor and politics, but they usually align around a few key themes like 1) always win (even better when someone else has to lose) 2) never show weakness and 3) make sure you get credit (or as 2Pac put it so many times, "I gotta get mine. You gotta get yours.").