Thanks all for your interesting insights here. I'm a bit late getting back to the discussion so I'll toss in a few random points that have occurred to me rather than replying to any one post in particular.
Re narcissist vs sociopath/psychopath. Narcissism is a symptom of both Antisocial personality disorder(psychopath/sociopath) and NPD (obviously). The main difference between the two is that narcissists *care what people think of them*. Both are manipulative, personally exploitative, lacking in empathy, compulsive liars and see others as objects to be used, but narcissists *need* other people to see them as being fabulous; psychopaths don't care what people think of them, as long as they can *get what they want* from them. If you want to get Freudian - narcissists are all about ego; psychopaths are all about id (base desires).
Which makes our G such a classic textbook NPD, with his whole need to portray himself as the big man about town. I was interested to see that even his brief profile on one of those dating sites betrayed his rampant narcissism: in the profile sections on "smoking/drinking" he posted (words to the effect of) "I do not smoke" "I do not drink" - he even had to insert an "I" into a simple yes/no answer, lol.
Something else that has come up in the discussion over whether he wanted to dump Allison to be with TM or vice versa - the answer I'd suggest is neither. Two things:
(1) a narcissist's whole raison d'etre is securing sources of narcissistic supply (other people, aka victims, who look up to the narcissist, reassure him that he's awesome, and *have emotional reactions to his behaviour*, thereby supplying the emotional stimulus he lacks. They never have just one - you need a backup in case the first one comes to her senses and runs off. Three or four is better.
(2) having two (or more) lovers fighting over him is the narcissist's ideal - what an ego trip! Losing one or the other is a massive loss to the narc (literally a "narcissistic wound"). Even if he views both of them as stupid, inferior, annoying women, he also needs them, much more than they need him, because without them he is literally nothing - his whole (false) ego is constructed upon the feedback from other people.
Re the BC family - narcissists collect victims. Victims tend to be kind, generous, giving, non-critical individuals, or other personality disorders like histrionic PD (drama queens) or borderline PD (low self-esteem, poor boundaries), that match particularly well with Narcs. So in a narcissistic family you'll have a fairly even breakup between narcissists and trained victims - they're not all bad, they're just conditioned by a lifetime of systematic abuse. (and on that topic my guess is NBC - NPD; EBC - histrionic, OW - borderline, other son "relatively normal guy who escaped as soon as he could but tending towards low self-esteem/borderline").
