(which is typical of him if his behavior with others is anything to suggest -- he has a tendency to get attached quickly or not at all, whether or not he shows it)

Interesting point. I guess I can see this in his relationships with Teyla and McKay, Ronan, possibly Ford and a couple of others. And of course the city itself - you can tell he loves it there. To extend that into wankery (because we all enjoy a good wank), maybe that comes from his childhood as the son of an officer, moving around all the time and having to continually make new friends? Maybe led to him appreciating certain qualities in people that will make him get attached quickly?

even in the case of Mckay who adapts himself to be the personal "enemy" that people want to have there to fight

Hmm... I'm sure that I agree with this point. At least, I can't see McKay doing this consciously, making a conscious effort to be that, as I can with Sheppard.

Hey, I just wanted to say thank you for making me think about this. I've never subscribed to the Sheppard-as-cad interpretation, but I hadn't thought about it as deeply as this. It's been incredibly helpful :) And now I know you have all these thinky thoughts, there may be fic-related bugging in your future *saeva runs away screaming*