I'ts worth mentioning that as I'm hopelessly behind, the stuff I liked this year isn't particularly current, but it's still good. It's still good!
My favourite fic I read this year has to be Samarkand Nights, by Hyarrowen. It's an old fic (2011) for an old fandom (Shakespeare's Henry V, believe it or not) but anyone who has ever read any of my stuff knows that I'm a real sucker for travelogues, and this story doesn't disappoint. This is part of a series -the second story in Henry's Journey-and I'm not familiar with the characters-but my God, it works. It works well. The descriptions of the landscape and period details are spot on and very beautiful. Plus, she has another series called Jumping o'er Times where the same characters time travel and fight dinosaurs. Warning for very mild slash.
The fic that made me laugh most this year is Steve Rogers at 100: Celebrating Captain America on Film by eleveninches, Febricant, hellotailor, M_Leigh, neenya and tigrrmilk. This is a spot-on and very funny fic about Captain America and Bucky Barnes reviewing all the movies about Captain America and Bucky Barnes that have been made since Steve Rogers went away.The beginning is dry, but it warms up.Contains movie posters. It's not a new fic, so you might have read this one. Regardless, it's still ten thousand words of pure comedy gold.
The smartest fic I read this year is Wasp Harvest by Overlithe. You know how you read books by authors and realize pretty instantaneously that they're much smarter than you? This is one of the few times I've felt this in a fic. Contains historical footnotes-and you know how I love historical footnotes. Bucky Barnes's transformation under the hands-and syringes-of Armin Zola and Alexander Pierce. Warning for being extremely long and also extremely dark. I'm not kidding about the darkness, so read with the light on.
As a unicorn chaser for that last one, here's a funny piece of fluff. From A Seed by theorytale, in which Loki convinces Tony Stark he gave birth to a pot plant-mild warnings for mpreg but you know, Loki, and for a more recent fandom, You're Awful by zamwessel, in which the ginger mook from Star Wars; The Force Awakens gives Kylo Ren a piece of his mind. Or several pieces. Funny crackfic.