I want to share with you a post by Richard Grannon which explains really good what is happening inside the narcissist, why empaths are so drawn to them, and comes up with an approach on how they could be healed.
Healing the narcissist
I've seen some of R. Grannon's videos and they are often good, but as a former therapist, I disagree with this one. I do not see people who really suffer from NPD being cured. There are many people with just some narcissistic tendencies who can be helped, but a full blown one is hopeless, and your best strategy is to move at least 3 days full drive away from them and go 'no contact'. Many therapists will even require that kind of move before they will treat you for what the Narc has done to you.