Double Trouble, is a re-write of the HTTYD 1 story, the exact same story, but with a added character. In this version of the story, Hiccup has an identical twin sister named Hailey, someone he's very close too, her being his only friend, and in his mind, his only family. There is only one Nightfury, though in later one shots, it'll be revealed that Hailey gets her own dragon. See Hiccup as you never could, as a protective brother.
3 parts