Brynhild stands at the tragic centre of the Norse Volsung legend, and her story turns on a single act of divine disobedience. A valkyrie in Odin's service, she grants victory in battle to the wrong king against the god's decree, and for this Odin pricks her with a sleep-thorn and condemns her to mortal life and marriage, a demotion from chooser of the slain to woman bound by a husband. Ringed by fire on the mountain, she is awakened by the hero Sigurd, and the two exchange vows.
The tragedy is set in motion by a potion of forgetfulness: Sigurd, his memory clouded, wins her instead for his friend Gunnar by riding through the flames in Gunnar's shape, and Brynhild, betrayed and shamed, engineers Sigurd's death and then joins him on the funeral pyre. The tale survives in two related bodies of text, the older, starker verses of the Poetic Edda and the prose Volsunga Saga, and it is the ultimate source of the Brunnhilde of Wagner's Ring. She embodies a recurring Norse theme: fate, once set, is not evaded, and honour is answered in blood.