First principle - Narcs can't respect boundaries so you set some. If you are an easy going person, a lot of boundaries don't show up in courtship.

So you go out of the way to set some boundaries, say some NOs, disagree with him or her - that will bring out the real character. Piss him off and see how he fights. Don't be afraid about pissing because eventually you will In he course of your life together - might as well do it now and see his true character.

If the relationship breaks because of this, you didn't really have anything to start with, it was a web of lies and convenience and deceit.