Helgi was reportedly the son-in-law of Sigurd Snake-in-the-Eye (one of Ragnar Lodbrok's sons) and Blaeja, the daughter of king Aelle II of Northumbria.
"Sigurd Hjort was the name of a king in Ringerike, who was stouter and stronger than any other man, and his equal could not be seen for a handsome appearance.
His father was Helge Hvasse (the Sharp); and his mother was Aslaug, a daughter of Sigurd the snake-eyed, who again was a son of Ragnar Lodbrok.
It is related in regard to Sigurd's death that he had a custom of riding out quite alone in the uninhabited forest to hunt the wild beasts that are hurtful to man, and he was always very eager at this sport.
[1] Traditional sources state that Sigurd Hart was only 12 years old when he slew a berserker named Hildibrand in a duel, and 11 other men.