While this is very interesting, in practical terms it is irrelevant. The most fruitless and painful thing for someone involved with a narcissist to do is put any effort at all into "understanding" him/her. That is the food a narcissist feeds on, and it just keeps the partner locked ever more tightly in the myth that if only he/she is more understanding, loving, grateful, self negating, etc etc etc, the narcissist will miraculously change to become the loving person they really are deep deep deep deep down inside. Of course, this will never happen, but many many many innocent people's lives and psyches will be damaged, some permanently and irrevocably.