I discovered Twilight fan fiction by accident, and some of these novels rank among the best I have ever read, ever. What did I do before I discovered fan fiction? Dunno. Can't remember.
On Twitter I am @sonofsilly (But I am the mom, to some human sons and a doggie-son.)
I also read in the Merlin fandom, and particularly love the following:
-The Colour of Cartoon Sunshine by Junkshop_Disco
-Maybe the Seaside is the Place by Junkshop_Disco
-Refuge by Magnolia822
-World Enough and Time by Neathsunnyskies
Some of my favorite stories have been pulled. Where did they go?
-Hydraulic Level 5 by Gondolier
-Clockwork by Derdriu oFaolain
Get your hands on a copy if you can.