I think if you maintain your ditance without waivering it might grab the attention of your friends. I love to get involved in a conversation, but it’s always apparent to everyone in the conversation that I lose interest once gossip becomes the topic of conversation. Like if we are at a restaurant, I will just eat or get something for my food while everyone else is involved.
After a while, they realize that you aren’t interested. You and I both know that narcissist can be entertaining and interesting. They are performers! If you say something about your perception of this person being a taker/“n” they may bypass what you have to say. If they are close enough friends and value what you have to say and haven’t been sucked into the drama…I would say something. If that’s not the case, then just avoid conversations where the “n” takes center stage and find something more interesting. You can try to save your friends from the heartbreak that could occur and if they bypass what you say, then just be there as a voice of reason when the storm comes in broad view.
I wish you best of hope on this.