Fenris Thorston

Fenris is one of Ruffnut and Tuffnut's uncles, mentioned in the episode "King of Dragons, Part 2".

Remembered by Ruffnut and Tuffnut
After discovering the location of the King of Dragons on Berserker Island, Tuffnut believes that his uncle Fenris is underneath the island. He then recites a poem he used to adress Fenris when he was a child. Astrid then cuts Tuffnut off, telling him that Fenris has nothing to do with their situation. Later, when Hiccup gets out of the cave, bringing the King of Dragons' egg, Tuffnut asks if Fenris helped him, remarking how the egg has his uncle,s fingerprints on it. Hiccup simply replies "Sure, why not?", implying that he liked Tuffnut's story.

Trivia

 * Fenris, or Fenrir, is a giant wolf in the Norse Mythology, one of Loki's offsprings.