For a second I thought that I may be narcissistic, but then I realized that there is a difference between narcissism and introspection. And that I generally am the shit, simple as that.
However, my reading on the topic did help me to identify my ex as a true narcissist.
We were together for six miserable years so I can tell you all about the negative side the personality.
From a relationship perspective the person is incapable of any empathy or compromise. In order to work on a balanced level the narcissit's, its all about me, throws a chain reaction on the other end to be all about you, otherwise it really is ALL about them. Because the narissist cannot view the world from any other perspective, you cannot say things like "that hurts my feelings" because they won't care. If you need compromise in a relationship, you have to say "what you are doing is going to hurt YOUR feeling" as the relationship takes on a punishing parent to disobediant child attitude.
The nacissist will only look at how things affect them. Its like they mentally tapped out a five and never realized that the world does not revolve around them. The are constant victims instead of being self perceived as failures. Fix everything in a narcissistic life, and if they hold onto their self depreciating esteem they will start to blame you for anything they feel is the reason they suck. Basically they will turn on you in order to remain in a position that absolves them of responsibility.
When dealing up close with narcissits, one has to hold a very strong personality in order to not get sucked into their games they play with others as well as themselves. You must be fair yet authoritarian, as that is the only way to produce any form of positive feedback from them, and even then, expect them to become insecure due to the fact that you seemed to have the answer, and they did not.
My ex used to tell me " the only way I'll pay attention or learn anything is if shit hits the fan". This is the perfect summary of the narssisist. They only budge if they become uncomfortable. Otherwise its a steady stream of self motivated, premature, and ignorant actions that fuel their need, as someone already said, for constant validation.
They are also the royalty of false promises with out any follow through. No one really interacts with a narcissist, only outside of them. I recommend against actively engaging these types of people.