The Narc has a edifice of carefully built up layers, as bricks cemented on a building. This edifice can only be brought down with great attention to it and a great deal of pain.
Most Narcs will not do this. However, sometimes great tragedy will force a Narc to unravel this edifice, when it is suffocating the person, and he must. Short of this, I don’t think it will happen. Usually, it will not happen with even this, as the edifice is so tightly constructed.
If one has to have a relationship with a Narc, as many do, there are things which will make the navigation easier.
The person cannot see you beyond how you make him feel and look. Your inner landscape is of no interest to him, other than an annoyance. He may appear to put up with it. However, his eyes will glaze over, as you muse about inner workings of yourself.
This is very important and usually learned by screwing up. You must hold power over him. He must know that you can put him in his place, in some way that will hurt.
You must bring the stick out, at times, to remind him.
He hates your flaws. He wants you to be perfect. He will take your flaws and beat you over the head with them, if/when he can. Refer to Number 2 for how to deal with this.