I apologize for writing such an explosive post and then disappearing. Thank you all for your beautiful responses.

Aculady, your response in particular... (sounds like you may have spent some money at Games Workshop as well???) The amount of work you put into helping your son is breathtaking, and, honestly... I could not help feeling extremely exhausted as I read that. I have tried a similar approach with my son, for example a few days ago he wanted to talk about the Boer War and I did manage to turn that into a long conversation about the forces of history and why the Industrial Revolution happened in England. That was nice. But in general, attempting to explain the world through the lens of military history is something I can only do for short periods. It just freaks me out, and feels too much like I am feeding his obsessions.

I don't really think he is AS, in fact when he was very small I would have said he was very "un-AS"-- he seemed unusually engaged in people, both adults and his peers-- well beyond his agemates. It is only over the year or so (and it's getting worse) that he seems to be talking at people, not too them-- so maybe that's why I more worried about feeding his obsession, and less willing to adapt to them or use them as a means of teaching him.