Regin wished to possess the treasure which his brother guarded, and to this end forged a great sword for Sigurd, but it broke the first time it was tested, and Sigurd had his father's sword reassembled and re-forged, and Gram stood every test. By cunningly stabbing the monster from underneath, Sigurd succeeded in slaying Fafnir, thus gaining both wealth and wisdom (by licking the blood of the slain dragon), since Fafnir was said to have understood the language of birds. When he realized that Regin intended to kill him for the gold, Sigurd slew him before carrying it away himself.
Sigurd then went to free the Valkyrie maiden Brunhilde, who lay in a magical sleep, cast there by Odin, for daring to rise above his wishes. But Brunhilde had sworn only to marry the man who could ride through the fire that surrounded her dwelling. Gunnar wanted her, but could not perform the feat, but Sigurd in Gunnar's shape did so. Thus Brunhilde agreed to marry Gunnar.