Why They Don't Protect Or Help

Make no mistake~ Narcissists, regardless of their relationship with a target (parent, sibling, "friend", partner, coworker, relative, classmate, employer, etc.)
when a target gets abused, manipulated, or neglected by someone else.
They will give an abusive person ACCESS to a target. They will set up a target to get exposed to abusive people. They will NOT stand up for a target against disrespect or abuse, they will stand aside and let it happen. They will LET others take a target's possessions, violate their personal space and boundaries, disrespect them (right in front of them even), and sabotage, backstab, threaten, trash, and manipulate them.

WHY? Because their goal is to weaken the target, and other people doing that work is of course much better than doing it themselves. They won't get blamed, for one, and they don't have to actually do anything except stand back. When the other person is done, the target is even more malleable and ripe for targeting than before. Also, they now have yet another ally in their "gang" against the target.
Of course their defense will always be blaming the target, calling the target "paranoid", or "emotional", or "controlling", or "bitchy", or a "dick", etc etc AD NAUSEUM. The facts remain, however, regardless of how they try to twist them in their favor and against the target.
Healthy people don't target others, period. They don't disrespect others, they don't invade their boundaries or their space, they don't try to provoke others. Healthy people WANT others to feel HAPPY and SECURE, and be successful. They don't try to test, they don't take, they don't lie, they don't manipulate, they don't invade, and they DEFINITELY don't stand aside and let someone disrespect, steal from, or abuse another person.