I love Le Guin's The Left Hand of Darkness! That is another world I want a lot more fandom AUs to be set in. (Hey, when you're done with your HP one and your vampire one, you should do a Sherlock AU set in LHoD! Mycroft would be perfect swanning around Ehrenrang playing at shifgrethor, and Sherlock would either be the best Weaver in Karhide, or hate the Handdarata with a passion, or do a lot of risky experiments with foretelling-related drugs. Or all three. Plus I suspect in a Gethenian AU Sherlock and Mycroft would have a kid together, which would be... interesting. I would comment on John, but John is pretty much just John in every AU.)

And thank you for the mention of the other books! I will have to look them up.