In the Völsunga saga, Sigurd kills the dragon Fafnir. Fafnir was originally a dwarf who transformed into a dragon after greedily claiming the treasure of Andvari, including a cursed ring.
Sigurd is urged to confront Fafnir by Regin, Fafnir’s brother and Sigurd’s foster father. Regin reforges the broken sword Gram for him. Sigurd hides in a pit beneath the dragon’s path and thrusts Gram upward into Fafnir’s heart.
After the killing, Sigurd roasts Fafnir’s heart for Regin. When he touches the heart and tastes the blood, he gains the ability to understand birds, who warn him that Regin plans to betray him. Sigurd therefore kills Regin as well.
The Völsunga saga’s Sigurd is closely related to the Germanic legendary Siegfried, but the names and details differ between traditions.