Judith Acosta, Huffington Post: Narcissists are very nice until they don't get their way. They are great charmers and can get most people to do and accept things that they wouldn't in their wildest dreams imagine themselves doing or accepting. Narcissists are often very adept con artists.
Narcissism, in psycho-therapeutic parlance, is a term used to indicate a superficial personality type with a hyper-inflated sense of self to compensate for a grievously wounded core. They need a huge amount of support and reinforcement or applause to feel that they have any existence at all... A narcissist is simply someone who puts himself in the center of the universe and fully, comfortably, and syntonically expects you to do the same for him.
As a result, what they want is paramount in any relationship -- intimate or fleeting. They are people who don't accept 'no' for answer easily because it so threatens either their plan, their sense of self-worth, or both. In order to keep things moving where they want them to go, they will manipulate with sweetness and charm. If that doesn't work, they will lie. And if that doesn't work, in many cases (though not all) they will rage. Sometimes that rage is malignant and can result in profound emotional or bodily harm to others...
Because our culture puts such a premium on niceness, charm, and pleasure, ordinary, good people are put at a disadvantage when it comes to discernment. A narcissist can appear quite innocent because she has so mastered the technique of ingratiation, so much so that she can make you feel that you have somehow committed a terrible injustice by denying her X or Y or Z as she positions herself as the victim. As Gavin de Becker points out, in The Gift of Fear, this failure to see behind the mask of niceness can make the difference between life and death.