The pathology of npd is very much about the art of mental projection.
Its tricky you see- what the narcissist refrains from showing and displaying to his victims, his cheery and kind false self, the narcissist also taught to his victim who he isn’t.
The narcissist teaches his victims how they should interact with him, this also takes place with all human interactions. We as humans, learn how to converse and interact with people on a one on one basis. For example, your best friend knowing you get upset if ignored thus, your best friend ensuring they do not make you feel ignored in return.
So when the narcissist refrains from behaving as his usual false self and starts to change and become abusive, the victim is confused by this because it goes against the grain of what the victim already knows about the narcissists false self. So what does the victim do?? Begins to unknowingly behave like the narcissist. The victim will yell as a result of the gaslighting and manipulation, react to reality to which the narcissist denies, etc etc
So..when the narcissists false self vanishes, the narcissist also projects onto his victim who he really is. This projection makes the narcissist’s victims think they are the narcissists.