Hi Pea,
My sister is 26, her boyfriend works long hours so she tends to play more when he's at work and she's not. I don't know if it's possible to network but I never have, and as far as I know she doesn't either. Same goes for forums etc, neither of us really sees it as a social game.
As for the way we play, I'd say definitely different personas, particularly as sometimes you have to do things cos the game demands it, rather than because it's what you would do yourself. I don't really know what makes it addictive, I played the PSP version and got some satisfaction out of completing it, but wouldn't go back to it again, whereas she plays the PC version which I gather is different and lends itself more to playing without ever really feeling like you've completed it. Hope that helps!