As with so many things, the Greeks had a word for excessive pride or selfishness. What they called hubris, we now usually think of as narcissism. Freud considered healthy narcissism to be an essential part of development. While everyone may need a healthy dose of self-love, some people take it to extremes. Working with a narcissist can be challenging.
Narcissists have an attitude of superiority. They are after power and are not hesitant to use whatever means is available to get it. While a narcissist may seem to be concerned with other people, they really only express socially expected empathy when it is convenient to do so. The narcissist doesn’t have a strong moral compass and so is changeable and easily bored. The childhood of the narcissist might have been traumatic, or else the narcissist merely grew up with a sense of entitlement. They overestimate their own abilities and have an excessive need for approval. Unfortunately for those who must deal with a narcissist, they are also often very charming.
If you have no choice but to interact with a narcissist, listen to what they say, nod your head, but don’t believe a word of it. Go out of your way to accommodate them, but make sure you are emotional and financially independent of them. Know yourself and define what you hope to get from the relationship. Above all, develop strategies to minimize harm to yourself.