There are some popular science books on narcissism that do a good job of giving an overview of contemporary research. One I read was "The New Science of Narcissism" and another one, I think "Disarming the Narcissist" but I can't remember the exact name. They were recommended by my therapist to deal with my father and brother whom she said seemed to have some narcissistic tendencies (but who she couldn't diagnose for obvious reasons).

The first book talks about grandiose narcissism and vulnerable narcissism which are ways to understand people who have Narcissistic Personality Disorder. The experiences of the people seemed very sad, it made me significantly more sympathetic and empathetic to people who seem to be narcissistic. I still keep my distance and I don't treat cast judgement anymore.