I know someone whos actually doing an interesting experiment with a narcissist where he's online pretending to be someone else and since he knows this woman is a narc, hes mentally prepared for the blows and has some himeself. She even stated the conversation by calling him a "rat" like she was the cat and he's the prey. But he quicly turmed the table around and now he's putting her down, and guess what? She's enraged and whiny because someone else is treating her like she usually treats others. So they can give that treatment but not receive it. Theyre weak!
Narcissists often attract other narcissists into exactly this kind of dyad.
If your catfishing friend is doing this wiith the intention of getting the other party to see himself and change, that won't happen and they'll just have a toxic battle that ends badly or one of them will become a flying monkey for the other. Narcissism involves an innate biological incapacity to perceive the humanity of the other. People who appear to be "reformed" narcissists are usually people who were not born wiith the disorder but who were behaving like narcissists because they were raised in a narcissistic family and learned the behavior. In the process of counseling a narcissistic family, a therapist often evaluates the victim's behavior initially as NPD but as sessions go on the true NPDs in the cluster separate themselves out and the victim ends up reparenting him or herself and learning new behavior.
A true NPD can cognitively reform by accepting external rules of behavior, but that is only a trade-off. The people around him have to accept that he is behaving well for his own reasons and because he has found an acceptable way to get his narcissistic supply.
But they should never let their guard down.
Now, sometimes it is a worthwhile strategy to make an open attack on a severe NPD if there is a good reason, such as helping a victim get protection by exposing the NPD to his deceived onlookers, but you have to plan such an attack carefully and you should only do it when you have full back-up of evidence to support your assertion that the NPD in question is seriously dangerous.
All NPD's are jerks, but only a certain percentage are truly dangerous. (A much larger percentage than most other groups, to be sure!)
Narcs baiting narcs is actually quite common. And pointless.