Putting the RO in romance

Had a brief discussion with Ama today about pairings for Hetalia Ro that work well in historical context, rather than the ubiquitous ambiguously modern fluff. Figured I might jot some things down here because otherwise I might not remember them. (I'd forget my head if it weren't screwed on.)

( Pairing list + a few notes + RO/NO detour because I have a one-track mind )