I have been dealing with my brother who has an advanced case of npd. For years it has been a cycle of abuse, laziness, arguments, competition, whining, stealing and then silence. This tends to run in our family. My Grandfather disowned his son for marrying a girl he didn't like. wound up giving his inheritance to the golden child, who has the same traits and on his deathbed badmouthed the rotten son for not doing as he asked. This disorder does run in families but will skip some, I like to say its on 2 separate rails. I never knew this until I did some research into my own mental problems related to him. That moment was like a heavenly light opening up for me and I know what I must do.
My mistake was to not look into this behavior and start a business. The sense of selfishness and entitlement is huge and uncontrollable. Only gets worse over time as the mind regresses into infancy and childhood primal desires. Feeding the monster! Anything will feed it and thrives on contact. It will steal from you and hold hostage only to destroy in a fit of rage and make silly excuses designed to argue.
You MUST leave before he/she leaves you and they will drop you like a rock in water. In my case my brother steals items to hold hostage (Lure lines). Cut them as it's not worth it. How many items pass thru our hands over lifetime? is it really worth it?
In my case this made the family aware that I cut ties. I didn't attend my mother's funeral, let my items go and totally ignore calls and messages. Interesting the family has recently contacted me about his problems and now has understanding but still feeds him. His raging anger directed at me dropped and got focused onto his wife. I cannot help them though, I just say it's a tough situation and move on the conversation.
You have to understand that this mind is not functioning normally and will not be fixed....EVER! Narcs hate stoic figures, silence, being "found out", police and other's success.
It's hard to drop your family but many will come back only if you leave first. Also never badmouth the family narc because he doesn't exist. After all family is what we make of it, not just sharing blood lines.