I agree with rooperi that Alekhine's Defense is a good choice for a psychological scene. However, I would have player B as Black play Alekhine's Defense:
The significance of this line is that old chess computers used to play 4...Ke6 to save the knight because they didn't value king safety.
What is the year in the setting of your story?
Thanks for your input... I still feel the specific defense isn't what I'm going for considering my hopes for the brashness of B's opening ... but perhaps that aspect could be revisitied.
As for your question: The year is immaterial (considering it's another world/universe) but the cultural setting is analoguous for the old world from the 11th through late 14th centuries. It's a pretty diverse place (culturally, historically, ecologically) so it's hard to point to a 'setting'... the setting of this vignette is in the ample (yet clutterd) quarters of an elite intellectual.
Your scenario is rather elaborate.
As an alternative you might do as others have done and base your fictional game on a real game; the one I have in mind is a blitz game between Kasparov and Georgiev (http://www.chessgames.com/perl/chessgame?gid=1258478). Kasparov has much the better of the game and is left with queen and bishop against Georgiev's sole king. He is in the process of delivering mate when he blunders and creates a stalemate.