Introduction
Regin was a son of Hreidmar and a skilled smith, denied any share of the cursed gold by his brother Fafnir, who had murdered their father and kept the hoard for himself.
Family
Foster-Father and Betrayer
Regin took in the young Sigurd, heir of the Volsungs, as his foster son, training him and reforging the shattered pieces of his father Sigmund's sword into the mighty blade Gram. He urged Sigurd to kill Fafnir to reclaim the gold, secretly intending to have Sigurd do the dangerous work and then murder him to take the treasure alone. His plan unraveled when Sigurd, having tasted Fafnir's heart-blood while roasting it at Regin's own request, gained the sudden ability to understand the speech of birds — who promptly warned him of Regin's plot. Sigurd killed Regin before he could act, becoming the sole heir to the cursed hoard.
The Volsunga Saga and the Poetic Edda preserve the Norse-Icelandic form of this legend; the German Nibelungenlied recounts substantially the same events under different names (Sigurd as Siegfried, Brynhild as Brünnhilde, Atli as Etzel/Attila), reflecting a shared Germanic legendary tradition rather than a single fixed text.