In the far north lands of the Vikings stories are told of fights and feuds and foul deeds. The books of tales are called the Sagas and in one of them is featured Fáfnir (or Frænir) the son of the King of the Dwarfs, Hreidmar.
Fafnir was fair of face and brave and fearless and strong. He and his brothers Regin and Ótr guarded their father's house, which contained a fantastic hoard of gold. One day Ótr was killed by Loki, the trickster god, and Hreidmar was given blood money in return. But the gold was cursed and made the surviving brothers plot to kill their father. But Fáfnir wanted the gold all for himself.
As a mark of his greed Fáfnir was turned into a dragon (for the Vikings believed that dragons were greedy because they kept hoards of gold and jewels in their nests. Regin sent his foster-son Sigurd to kill the dragon and they feasted on the dragon's flesh.
Regin was still cursed by the gold and planned to kill Sigurd, but Sigurd had eaten the dragon's heart and so could understand the language of the birds. They warned him of Regin's approach and so he was ready for the attack. Regin fell in the ensuing fight and the curse was broken. Sigurd kept the gold for himself.