They're out there. Somewhere.

I don't want to sound pompous but I think I can almost call myself an expert on narcissism. I'm not a psychologist or psychiatrist but I've had the benefit of seeing things that these esteemed fellows have never seen. I've lived with one. I've had to deal with one. I have children with one. I've known one and her often bizarre, childlike and yet dangerous behaviour for a long, long time. So long in fact that I now know how she will behave and react in just about every situation. Its take me a long time to crystalise my thoughts on what is the actual driving force behind a narcissist, but it is quite simple really. The behaviours are listed endlessly - grandiosity, entitlement etc. etc., even the possible roots of narcissism are frequently discussed (spoiling upbringing, poor upbringing etc.) but I have never actually seen what is the actual cause of these behaviours being discussed-what is the reason for the grandiosity, entitlement etc. My belief is perfection. They need first of all to believe themselves to be perfect. They also need to believe, in order to feel validated in this belief, that others see them as perfect. Absolutely everything about them is about perfection. This perfection can come of course in a variety of guises and can I believe change quite rapidly over the course of a lifetime. It is an all-consuming need to feel and (in their view) appear perfect at whatever they choose to see as important in their life at that time. For example a dancer could believe herself to be the best dancer. If she then has children she would then divert her perfection quest into becoming the best parent. Or at least believing herself (and believing that others view her)to be the perfect parent. She will still view herself as having been the best dancer, but now parenting is so much more important.
All of us want to do the best at what we do. All of us need to think good things about ourselves. The narcissist however takes this to the nth degree. I believe that everything else that springs forth from the narcissist is a direct result of this constant need to believe in their own perfection and to feel that this is being mirrored back to them by friends, acquaintences, family-in fact just about everyone they come into contact with.
The reason living with one is such a traumatic, mind-bending experience is that you see the flaws behind the mask, the secrets behind closed doors, this is inevitable after a period, even allowing for the narcissist's fear of anyone getting too close. You then become a threat to their image (both self image and other image) and must be firstly disarmed and at some stage abandoned. The reason living with one is so destructive to one's self-esteem is that the narcissist quite happily makes herself feel better by bringing you down. Their reasons for doing this are twofold. First there is the simple reason that by diminishing you they feel superior, The second reason is in many ways far more destructive. By diminishing you they effectively invalidate your feelings, opinions and views on them. In other words, you have started seeing some of the flaws in them. They become aware of this at some level. They must diminish your standing, destroy you if necessary in order to reduce the value of your opininion of them. This is universal behaviour with narcissists. After a period of close contact with anyone we start seeing slight problems or even defects with their behaviour. If we love them we can accommodate these. This is intolerable for the narcissist however. Whether it be pointing out to them that their behaviour is less than perfect or, horror of horrors, telling others of their behaviour, your threat must be nullified. To a true narcissist this much more important than making the relationship work. You are expendable. Their self-image is ALL that matters.
You will not change a narcissist, it is an excercise in futility. They will never hear you or understand your views unless it adds to their image.