Hiccup Haddock I is the great-great-great grandfather of Hiccup and Snotface Snotlout.
In his youth, Hiccup was pursued by a great dragon named Merciless (later known as the Green Death) who predicted that one day he would be killed by a child named Hiccup. The dragon he sent to kill Hiccup was the Wodensfang, who Hiccup befriended after untying him from a tree and treating his wound. The Wodensfang taught Hiccup Dragonese, and he in turn taught the Wodensfang norse. Hiccup became the first human to ride on a dragon's back. Hiccup I was given the dragon jewel by the Wodensfang, promising him he would not use this gift for evil. Hiccup defended himself by threatening Merciless with the jewel when he came to assassinate him. Hiccup made Merciless disband his dragon army and live again as a loner and then warned Merciless never to return to the Archipelago. Hiccup I used the dragon jewel to train dragons to farm, hunt, herd sheep and deer and in return they were treated as equals. The dragons were fed first at every hunt, sat around the fire with the men and gave their opinions before attacks. However, after Hiccup I's death his descendants do not keep the promise Hiccup made to the Wodensfang and begin to enslave dragons.