I'm BPD and I don't 'mirror' in the way NPD's mirror. Mine is more empathic ... as if I'm trying to see what another person feels so I can match it...almost like the old thing where if your partner or new date raises his glass to drink and you do the same without even thinking about it. It's a bonding thing, when BPD's do it.

NPD's, on the other hand are looking for a kind of guidance, not bonding. The interesting thing, of course, is how well BPD's and NPD's will mesh emotionally--for awhile. We both adapt to each others needs, until the NPD gets bored of us, which is inevitable...as the BPD will always require much more emotionally than the NPD is able or willing to give.

Of course, any discussion of this will be generalized as all NPD's (and BPD's for that matter) are individuals, and to catagorize them is unfair and short sighted. But I hope this helps a little in the understanding.