Yuletide recs

Recs for 18th CE RPF, Instrumentality of Mankind, Nirvana in Fire, Arm Joe, Earthsea, Dark Lord of Derkholm/Howl Series, Where Are You Going Where Have You Been, Scholomance, Tlön Uqbar Orbis Tertius, 3rd CE RPF - Tetrarchy - with two crossovers to physics/math fandom, so to speak (one is tagged Mathematics, the other is a stealth crossover) ( Cut. )