Wodensfang is the dragon sent to kill Hiccup Horrendous Haddock I.
Unfortunately for Wodensfang, he was caught in some branches and left to die, but Hiccup nursed him back to life. In return, Wodensfang taught Hiccup Dragonese and Hiccup taught him Norse. Wodensfang told Hiccup I where to find the Dragon Jewel and made him swear not to use it for evil. Hiccup I used the Jewel to teach dragon to fish, hunt and other stuff. Hiccup I then used the Jewel to banish Merciless from the Archipelago. After Hiccup I's death, humans started using the Jewel for their own purposes. Grimbeard the Ghastly, the last King of the Wilderwest, told Wodensfang to guard the Crown and kill anyone who tried to use that power again.
In the How to Steal a Dragon's Sword BookEdit
In How to Steal a Dragon's Sword, Hiccup meets Wodensfang while trying to retrieve the Crown. Wodensfang tells Hiccup about his ancestor. When Hiccup promises to use the Throne of the Wilderwest to free all dragons, Wodensfang agrees to let Hiccup take the crown and live. When Furious and the Red-Rage Dragon Rebellion attack, Wodensfang, the Windwalker and Toothless flee with Hiccup.