Pee Wee Herman Had It Right! Narcissists Don't Want To Hear Your Complaints (But Love Their Own)

Narcissists are all about how THEY get treated by others, but seem oblivious to the way others get treated.
They are very watchful and even hyper-sensitive to the way others treat them and interact with one another; if you had a conversation about it with one they might seem very empathetic and aware. However, start talking about how someone treated YOU, and you will see quite a different reactio...n.
They often interpret the behavior of others to be disrespectful, hostile, unfair or abusive toward them, often when it was quite the opposite, and they often project all kinds of negative connotations and intentions on what others say and do, especially if the person is someone they ENVY or FEAR.

However! Let someone they consider "below them" talk about unfairness, disrespect, injustice or crime toward them, and the reaction will be complete invalidation and rejection, no matter what the incident or situation was, or how severe the behavior. The Narcissist will metaphorically put his or her hands over their ears and go "Lalalalalaa!" like Paul Reubens used to do. 

No matter what the situation was, or what the events were, Narcissists will almost always blame the victim or target, unless they have something to gain by sympathizing with the victim.

So when your Narc. friend doesn't seem to care how his or her other friends or family members treat you, it's because he/she DOESN"T CARE.

To stand up for you would be too much work, and you're not worth that to a Narc. It wouldn't GAIN THEM anything, which is very important, and it might actually COST them something, like status, position, or admiration. They also might be afraid of those people, since it's not uncommon for Narcissists to have the same pattern as Narc. targets in choosing "friends" and partners; their associates might also be Narcs who are just waiting for an excuse to 'bite'. And further, the odds are that they are actually enjoying the fact that you are getting treated with disrespect.

The Narcissist can't do checks and balances.
He or she is not going to say "Hey all your friends and acquaintances treat me with respect and kindness, but many of mine treat you with total disdain or disrespect, that's not fair!"

They aren't going to say "Hey you are always polite and considerate to me, and keep your word to me, and help me when I ask. I respect you for that, and I will also treat you with the same consideration and respect."

They aren't going to say "Hey I noticed that waitress, clerk, salesperson, or other person treated me with respect, but treated you with DISRESPECT."

They don't CARE, and they probably LIKE IT anyway, because they see it as them getting elevated and you getting "kept in your place."
(Narcissists are usually obsessed with 'hierarchy' and feel GOOD when a person treats them better than someone else, even what the person being disrespected is their own child, friend, partner, or relative. It reaffirms their feeling of self-importance, which is what they substitute for their missing self-esteem.)