Appearance and personality
Asgeir is a man of average build, with long hair, a moustache and a braided beard. His weapon of choice appears to be a sword. Asgeir seems to be very intelligent and is oftentimes seen giving advice to and watching over Thorkellー or being in charge of battle strategics (as seen in the 'Baltic Sea War' arc).
He was first introduced to the story in chapter 21 when briefly interacting with Thorkell, followed by a few similarly minor background appearances. Asgeir is spotlighted for the first time when interfering in the fight between Thorkell and Thorfinn, threatening to kill the latter.
Asgeir and other characters
ThorkellAsgeir appears to have a very close bond with Thorkell. He is one of the few characters Thorkell seeks to meet at eyelevel in conversation, listens to Asgeir's advice and puts him in charge of strategics and planning (as seen in the Baltic Sea War chapters onward). Although Asgeir breaks up the duel of Thorfinn and Thorkell and thereby dishonours Thorkell, he appears to accept Asgeirs commands (although reluctantly) which shows a great level of respect on Thorkells side. Asgeir seems to reciprocrate this feeling of respect as he adresses him with his rank 'Boss (大将)' instead of his first name in public. He appears to know his boss very well and does not seem to be afraid of him because Asgeir does not back away even when Thorkell actively attempts to strangle him. The Vinland Saga anime director Shûhei Yabuta remarked that their bond is interesting and unique and that he plans to explore it even further in the anime adaptation.