The Crown of the Summer Court
Author : astolat
Rating : NC17
Summary : "The king sent me to get you," Merlin said, with a tone that implied strongly that he wasn't rolling his eyes where Arthur could see, but just wait until his back was turned. "He said you're to get changed into formal clothes and meet him in the Great Hall, there's a delegation coming from the Summer Court."
Why I loved it : It was probably the first fic in the Merlin fandom that really left a mark on me. Since then I re-read it at least 5 more times and each time, I fell in love with the universe depicted in that fic. The relationship with Merlin and Arthur is perfect, the Elves are wonderfully described and the story itself is captivating!