The two fall in love, and Sigrún tells Helgi that her father Högni has promised her to Höðbroddr, the son of king Granmarr. Helgi invades Granmar's kingdom and slays anyone opposing their relationship. Only Sigrún's brother Dagr is left alive on condition that he swears fealty to Helgi.
Dagr is however obliged by honour to avenge his brothers and after having summoned Odin, the god gives him a spear. In a place called Fjoturlund, Dagr kills Helgi and goes back to his sister to tell her of his deed. Sigrún puts Dagr under a powerful curse after which he is obliged to live on carrion in the woods.
Helgi is put in a barrow, but returns from Valhalla one last time so that the two can spend a night together.
Sigrún appeared in the 2018 video game God of War, in which she is the Valkyrie Queen. She can be fought by the player after defeating eight other Valkyries. Her fight is considered to be one of the most difficult and demanding encounters in the franchise.[4]
In 2022, she also appeared in God of War Ragnarök. But this time, she was an ally with Kratos, Freya, Mimir, Atreus and the shield maidens—her sisters. She and the other eight Valkyries, her sisters, are now free of the corruption spells of Odin thanks to the events which happened in God of War.
In the series The Dresden Files, Sigrun, more commonly referred to as "Gard", is a warrior in the service of Monoc Securities, headed by Donar Vadderung. Vaddering is a being who is also Odin and Santa Claus.