[jluetjen]

My only additional observation about the two examples that I've met (one a Special Forces with time in Viet Nam, one a SEAL) is that they both shared a deep intensity. Not that kind that you can see from a mile away like in the movies. Nope, both of these guys were pleasant, professional and could be "goof balls". But after you'd been around them for a while and you got to know them, you'd start to sense that whatever you saw on the outside, the inside was solid steel. If the order was given to kill you, you'd be promptly dispatched without any hysterics, and then they would go back to whatever they were doing.

That, and they both were very competitive.