A Narcissist (NPD) at any age acts like a spoiled child.
The narcissist is fixated at a developmental stage (from childhood to adulthood) in which the differentiation between the self and others is blurred. Over the years different explanations for this childish behavior/characteristic have emerged:
The narcissist remains stuck at the infantile level, displaying many of the characteristics of the omnipotent and invulnerable child. (Kohut, 1977)
The ability to walk gives the child a whole new perspective of the world around him. This new ability endows the child with a sense of grandiosity and omnipotence which closely resemble the narcissist's behavior. However, reality soon catches up with the child as the child enters the rapprochement subphase (age 14 to 24 months). At this stage the child discovers that he or she is not omnipotent, that there are limits to what he or she can do. According to Kernberg if the child is severely frustrated at this stage he or she can adapt by re-fusing or returning to the practicing subphase, which affords him the security of grandiosity and omnipotence (Kernberg, 1976).
The narcissistically injured child is thus told "Don't be who you are, be who I need you to be. Who you are disappoints me, threatens me angers me, overstimulates me. Be what I want and I will love you" (Johnson, 1987)
It is apparent then that the narcissist maintains the infantile illusion of being merged to the object (the mother etc.). At a psychological level he or she experiences difficulties in differentiating the self from others. It is the extent of this inability to distinguish personal boundaries which determines the severity of the narcissistic disorder (Johnson, 1987).
In the case of the narcissist, it is the shattering of the archetypal image of the mother which leads to the narcissistic manifestation. The primordial image of the mother symbolizes paradise, to the extent that the environment of the child is perfectly designed to meet his or her needs. No mother, however, can realistically fulfill the child's archetypal expectations. Nevertheless, so long as the mother reasonably fulfills the child's needs he or she will develop 'normally'. It is only when the mother fails to be a 'good enough mother', that the narcissistic condition will occur (Asper, 1993).
"the negativized ego of the narcissistically disturbed person is characterized by strong defense mechanisms and ego rigidity. A person with this disturbance has distanced himself from the painful emotions of negative experiences and has become egoistic, egocentric, and narcissistic" (Asper, 1993)
French psychiatrist Jacques Lacan's take on childhood
Lacan replaced Freud's postulated oral, anal and genital stages of child development with his own pre-mirror, mirror and post-mirror stages. During its first six months of existence, the child gradually fills the gap between bodily sensations and its perceptions of the outside world with symbols: fantasies with which its consciousness is merged. Then, over the next year or so, the child begins to recognize the outside as an extension or mirror of its own bodily image, absorbing at the same time an awareness of outside language: the meaning of the Other. But in the next, post-mirror stage, when the child begins to speak for itself, these traces of meaning are repressed because they represent something from the child has separated. But desire remains, hedged about by prohibitions and compromises, into adulthood, and provides the Id with its own logic, language and intentionality. From this early stage too comes any neurosis or psychosis that the adult may subsequently suffer from, these resulting from imbalances between the Imaginary, Symbolic and the Real. Ragland-Sullivan 1984
For more information on NPD characteristics
Narcissists are basically children, and they manipulate other people by making them react like children. A Narcissist will try to charm you, scare you or use whatever works to get his or her way. They have never grown up, so their ethics and emotions are childlike. If you deal with them you will soon find out they like to 'play'. At first this can appear amusing, until you discover that they are serious - they seek revenge for any slight, spreading rumors and lies about people they don't like (usually someone who has stood up to them, thwarting their childish ambitions). The greatest danger they pose is they want to bring everyone down to their level - they do this by manipulating the child in all of us. If they can push our buttons, get us going, convince people of their sincerity and goodness, then people will think good is bad, and bad is good. Narcissists hate maturity, they hate adults, they hate anyone who thinks (differently from them). Yes, they are hypocrites. They lie, cheat and steal - all the while putting up a front of being good and perfect. They are not intelligent per se, but they are cunning, and they will get their way if we let them. Like the bad apple that spoils the barrel, a Narcissist will slowly spread their disease to others, destroying lives, and wrecking havoc. S.M.
in a nut shell.... adult kids!