Here is a list of some traits of NPD (with detailed explanations), some of which I’ve never heard of, but make sense/or I have noticed (the tendency to not have opinions of their own is included here). Some are truly strange but accurate:
Odd sense of time/no sense of the passage of time.
Unusual/bizarre eating habits
Strange work habits
Bad gift givers; stingy
Lacks a sense of humor/doesn’t get jokes (but are often meanly sarcastic)
Naive and easily taken advantage of (!) — actually makes sense because they are oblivious to what is going on around them
Complain all the time; negative and pessimistic
Passive, lack initiative
No opinions of their own
Can’t follow conversations
May look much younger than they are
Self-sabotaging impulsivity
Occasional moods of giddy euphoria (not to be confused with real happiness — which is alien to narcissists)
Lucky Otters Haven 