Narcissists Have No Identity
If you read the article entitled "Narcissists: Shattered Persona, Split Personality," then you know that the pathologically narcissistic person is usually not a whole integrated self. They are actually a fractured or splintered, non-cohesive persona that is unable to function as a unified whole. They have no identity. Because their perception of themselves is so skewed and unrealistic, they are, in many ways, a stranger even to themselves. They are ignorant of their own flaws, their own talents, are unable in many cases to independently form opinions, and they often have serious difficulty making even simple decisions. This lack of basic identity is one of the reasons people with high levels of narcissism are said to have a personality disorder. Identity is one of the key pieces of the formation of personality. Without your identity, you would not know who you are or where you fit in. This is the problem that narcissists face.
But why do they have that problem? We know that in most cases, the narcissistic wound, which is the trauma or series of traumas (which can include ongoing treatment or environment) that happened to a person which caused them to develop pathological narcissism in the first place, usually happens at a very young age and is usually the result of abuse, neglect or both. This causes a fracturing of the original or core personality in the child, similar to the way multiple personalities develop. Because of this, the personality can never be fully actualized into what it was supposed to be or could have been. It has been shattered into different parts. The child is too busy trying to deal with the abuse or neglect. Their energy and focus is taken up with defending the self, and as abuse usually continues throughout childhood, this becomes the mind's primary job. Other jobs, such as the emotional development that normal children go through, are stunted or do not occur.
Many narcissists were also raised by narcissists themselves. Children raised by narcissists are shamed, abused and shocked out of their own feelings. Their feelings are repressed and pushed out, then replaced by their narcissistic parent's feelings. Consequently the child never learns to know, understand or trust their own feelings. They never learn to develop their own opinions or likes or any of the things that make us who we are. They become mimics, or chameleons, learning to ignore or even disdain their own feelings, likes and opinions in favor of the parent's because it's safer that way.
This is why adult narcissists have such unstable identities, often imitating others or making up an identity completely. They simply don't have one of their own. Even those who seem to have a strong personality are usually just emulating someone else. The narcissist learned at an early age that having your own thoughts, feelings and opinions is dangerous. So they repressed them and as adults, they can be literal strangers to themselves, often unable to make even basic choices or answer simple questions about themselves. They may be unable to answer questions about why they like things, why they do things or why they believe things. They just do.
This is probably another reason they use emotion as a guidepost for reality, however illogical this may be. With no identity or internal structure to lean against and rely on, they have only emotion to go by. This is one of the reasons for the Jekyll and Hyde behavior that we often see. With no internal ground to stand on and no true guiding force, they are simply flying by the seat of their pants in a world that probably makes very little sense to them. They have no authentic self to rely on and no way to emotionally understand what is going on or what to do, so they fake it. It would be the same as if a 4-year-old were suddenly saddled with the responsibilities, situations and decisions that adults must make. With no idea how to proceed or what to do and no way to get out of the situation, eventually they would just do what they see everybody else doing even if they didn't understand what was being done or why they were doing it. In a nutshell, that is how the pathologically narcissistic adult lives their life.
This leads to problems, because identity is how we differentiate ourselves from other people. You are black. I am white. You are a boy. I am a girl. You are tall. I am short. You like classical music. I like metal. You like to wear dresses. I prefer to wear jeans. When identity formation is corrupted, this creates an inability to differentiate between the self and others on a very fundamental level. This is part of the reason narcissists see everything and everybody as an extension of themselves, and it's one of the reasons you may notice that narcissists take criticism of things they like very seriously. These things are the only semblance of an identity that they have, and because they see everything and everyone as an extension of themselves, if you are insulting something they like, you are insulting them personally. Stating that you don't like a band or a TV show that they like may result in the narcissist stating that that means you dislike them, or that you only dislike these things because they do like them.
To non-narcissistic people, this comes across as a very odd and even delusional thing to say, but to the narcissist, these things are all they have that even comes close to an identity. They also see you as an extension of themselves - again, because they have no identity - and it is very distressing for them when your thoughts, feelings and opinions are different than theirs. It is, ironically, often exactly what their parents did to them. This very personal distress creates the feeling in them that things are chaotic and out of control and this is very difficult for them to tolerate. In response, the narcissist either adopts the other person's opinions, feelings and basic personality in favor of their own or rarely, tries to force the other person to adopt theirs - which was likely originally taken from somebody else. Either way it is a losing battle for everyone, with the narcissist feeling rejected and oppressed and the other person feeling attacked by a crazy person who does not understand that it's OK for people to think, believe and like different things.
It's an interesting and sad side effect to this behavior that the more narcissists attempt to emulate someone they admire, the more they feel controlled and dominated by that person. This is called engulfment, or a fear of engulfment. This results in anger and accusations from the narcissist, and the other person shaking their head in confusion. Narcissists suffer at varying degrees from a fear of rejection that is coupled with a fear of engulfment. This is the reason for the push-pull dynamic of their relationships, or what is often called the idealization/devaluation cycle.
We can see this most clearly with Borderline Personalities, but it is generally present in all types of narcissistic people. When they feel too close and too dominated by the other person's personality, they push back. They have spent their entire lives trying to separate from their environment and other people but never quite making it, so they want to protect what little identity they feel they do have. They push the other person away, attempting to create space and individuality, but their identity is actually wrapped up in the other person so they feel rejected and frightened by the distance they themselves have created. This is an endless cycle that can go on for months or even years, with the other person feeling like a yo-yo on a string because of the constant ups and downs created by the narcissist's lack of identity and inability to distinguish themselves from other people.
In the end, this is a deep, fundamental issue. The narcissist is like Humpty Dumpty put back together by Dr. Frankenstein. All of the pieces of the original identity were shattered and so the narcissist has tried to build a new one using bits and pieces taken from other people. The resulting identity is a sad, monstrous creation that cannot navigate the world around it and that no one can understand at all.