In Nordic mythology, the figure of the dragon was used as symbol of material greed, that is to say: it acquired a clearly negative sign, unlike some aspects of the Eastern mythology.
In the collection of Nordic poetic prose called –Volsung saga- it is told that Fafnir or Favnir was the son of the dwarf king Hreidmar, brother of Regin and Otr. Fafnir counted with the advantage of having a very long arm and an audacious soul; he was the strongest and more aggressive of the three brothers.
After Otr was assassinated by Loki, Hreidmar received the fortune of Andvari as a repayment for the loss of his son. Fafnir and Regin, both ambitious, assassinated their father and took his wealth. Nevertheless, Fafnir yearned to posses it everything, for that reason he became a dragon (Nordic symbol of greed) and disputed the gold to his brother. Regin, infuriated sent his son Sigurd to kill the dragon. He was successful, but he was tempted by the same sin that his father and his uncle: greed, and for that reason he ended up killing his own father, Regin. In The Song of the Nibelungs -as indicated below- there is another famous germanic hero who ends up defeating a dragon.
Fafnir or Fafner also appears in the Richard Wagner’s opera, The Ring of the Nibelungs, but he is portrayed as a giant able to safeguard the treasure with more fervor than a dwarf.
The Völsunga Saga is an Icelandic interpretation made by the end of the XIII century -century of origin and declination of the Volsung clan in which the existence of Sigurd, Brynhild and the destruction of the Burgundians - is documented. The German epic poem Nibelungenlied (The Song of the Nibelungs) is based on these old histories, that were popular in all the Germanic lands, but re-tells the traditional material and includes ingredients of the medieval scope of the court.
Nibelungenlied tells that Siegfried was the one who killed the dragon in the court of the Burgundians, thanks to this he could become owner of the treasure of the Nibelungs. After killing him, he bathed in the blood of this mythical animal and became an invulnerable man, except by a small weak point that was left, where a linden tree leaf fell while he was soaked with the blood of Fafnir: his back. Like Achilles' heel, his back will be the fatal spot that the treacherous Hagen will choose to betray him.