”Snake-in-the-eye” as part of Sigurd’s name denoted a physical characteristics. He was born with a mark in his left eye, described as the image of the Ouroboros (a snake biting its own tail) encircling the pupil of his eye. The snake mark had been prophesied by his mother Aslaug, the daughter of the Valkyrie Brynhildr.
In modern times, it has been suggested that the mark in Sigurd’s eye was a result of a congenital mutation of the PAX6 gene.
As a boy, Sigurd was close to his father and accompanied Ragnar on a hazardous expedition through Russia to the Hellespont. Later on in life he is said to have sojourned for a time in Scotland and the Scottish Islands.