According to the saga, Brunhild is the daughter of Budli and the sister of Atli. She is raised at a place called Hlymdalir by her King Heimir, who is married to her sister Bekkhild. At Hlymdalir she is known as "Hild under the helmet" ("Hildr und hjálmi") and is raised to be a shieldmaiden or valkyrie. When she is twelve years old, King Agnar steals Brunhild's magical swan shirt, and she is forced to swear an oath of loyalty to him. This causes her to intervene on Angar's behalf when he is fighting Hjálmgunnar, despite Odin's desire for Hjálmgunnar to win. As punishment, Odin stuck her with a sleep thorn and declared that she must marry. She swore that she would not awaken to marry unless a man came who knew no fear. Odin places the sleeping Brunhild on mount Hindarfjall and surrounds her with a wall of shields.