Born in 840, Aivor was the son of the Norse Viking drengr Gulbrandr and the shield-maiden Ragna of Denmark. He grew up in the Avaldnes settlement with his older sister who died during a fever epidemic when Aivor was only 6 years old. When he was 8 years old, he began training by his mother Ragna, who taught him to fight with the shield and the ax or the sword. The times when Gulbrandr was not plundering other countries, he taught his son to hunt animals in the forest and stealth to avoid being detected. Aivor became very skilled in the use of bearded axes, as well as having some mastery in the use of the single sword. When he was 17, he participated in his first raid by looting some villages on the Wessex coast.