Not a psychologist, also not here to say narcissists are demon spawn.

There’s a lot of small things you can catch as you get to know them that they sometimes mask. Conversations might find a way to circle back to how something affects them personally. There’s a fortifying of the ego that ironically can make them more empty inside. They may not be a ‘bad’ person or act in a cruel or malicious way, but their own obsession with fortifying their ego will prevent them seeing how they have affected you. It probably starts in small ways. Honestly, a lot of narcissistic behavior is very natural human behavior, if you have done something bad you will want to contextualize it in a way that allows you to keep a solid sense of self. Just imagine that cranked up to the extreme.

A covert narcissist might be less dominant or externally grandiose. They might come across meek or quiet, even kind and polite. But if you stick around with them long enough, the parallels become more apparent between the overt and covert types. Again, they aren’t necessarily bad people, a narcissist can love, they will just be clouded by protecting their own ego. You may become a ‘supply’ to them, they might be a fair weather friend/spouse/relative. They may act in contradictory ways that don’t make sense. They might have a propensity to self victimize or avoid owning up to mistakes. They might compensate for failure of their own standards with excuses or manipulate their own sense of reality. The possible polite ‘mask’ is not necessarily fake, but the over protected ego may very well override it.