According to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), there are nine specific symptoms or traits to look out for if you suspect that you are in a relationship with a person who has NPD (Narcissistic Personality Disorder).
These are the consistent traits that one would expect to find:
Self-perception of being unique, superior, and associated with high-status people and institutions
Needing continual admiration from others
These patterns of behavior have to be general and have shown themselves in childhood and continuing into adulthood in order for these characteristics to point towards a narcissistic personality disorder.
To understand what drives a narcissist, it is important to remember that they are not what they are trying so hard to appear to be (i.e. superior, special, perfect..etc.). In reality people with NPD are so insecure, that they need to cover this perceived weakness up with as much attention and admiration as they can get. Their only means of ataining self-esteem, is by having it reflected back by others, which is why achieving some sort of high status, is imperitive to a narcissist.
People who have NPD have no accountability and will not take ownership or responsibility for any wrong-doing or for the harm and suffering that they have caused others. This is an unconscious pattern that was cemented in early life. They can't let themselves think for a moment that they may have made a mistake or done anything wrong. They are unable to acknowledge even one little flaw because maintaining a perfect facade is a matter of life and death for them. Letting go of this rigidity and superficial appearance, is equal to holding on to power and there is nothing more important to a narcissist.
Danger! There are two main areas in which being involved with a narcissist is particularly damaging; if you have one or two narcissistic parents or if you are in a romantic relationship with a narcissist. You can read further about these two subjects in my blogs 'In love with a narcissist' and 'Child of a narcissist'.