First of all, proportion. Not everybody who has once or twice performed a selfish act is a narcissist. Not everybody who posts self-admiring photographs is a narcissist.
Generally, our tendency to hurl psychological labels at one another whenever a fuse blows rather empties those terms of content. In a world where everybody is special, nobody is special. Following the same logic, in a relationship where you are a narcissist every time you fail to leap to your partner's demands, narcissism has no distinct meaning.
Accordingly, this is not going to be a piece in the style of how to identify a narcissist in five simple signs. Emphatically not.
We came here to understand. Slowly.
Here is what will happen now. We will give an abbreviated working definition, and then detail the axes on which the narcissistic personality sits.
What is narcissism, broadly?
Narcissism has a prominent intrapersonal component and a prominent interpersonal one.
The intrapersonal component is an idealised self-image.
The interpersonal component is a constant search for esteem and admiration from the environment.
That is it.
And I return to the proportion I opened with. Both of those psychological blemishes are things every one of us falls into from time to time.
What distinguishes the clinical picture is not their presence but their rigidity — the fact that the person cannot function without the supply, and that the entire relational world is organised around obtaining it.
Which produces the single most useful practical marker, and it is not a trait of theirs. It is a fact about you: how you feel after time in their company. Ordinary difficult people leave you irritated. This leaves you diminished, and slightly unsure why, and gradually less certain of your own account of events.
That is worth more than any checklist, because it is an observation you can actually make.