I know someone who will swear up and down about how they were the scapegoated child and how victimized they were as a child when they were actually the golden child UNTIL they hit puberty and began disagreeing with the narc parent. And so this person then took out all of their rage on their younger sibling. It was horrifying to witness.
This individual has now shown themselves as a true narc and, not surprisingly, is still playing the victim in every ruined relationship they leave in the wake of their delusional and cruel behavior.