For those of you who knew your NPD's parents, did their parents seem to want to be the center of their lives?
Did they try to control the lives of their NPD Adult Children and forever seem to be dangling money in front of them?
Did they belittle and criticize their kids even into adulthood, in order to keep them in a dependent state?

just one word

YES!

both my PDIs (younger and older)

As a son of a PDI mother - it was always - always - ALWAYS about her.

Childhood, teens adulthood - her.

It was a real struggle to emotionally survive and separate my mother from my life even as a married man in my 20s AND in the military. I'm not a mummy's boy - in fact the exact reverse because of the way my mother was. BUT dear god she tried and tried and interfered in every relation I had. Any woman I showed a real interest in (even married) was deemed the "competition" with the added back stabbing and interference.

Narc the younger had the exact same maternal interference with the added bonus of being the scapegoat and with golden child sister. She just didn't have my father to balance the act - so that fruit fell too close to the tree.