With a name like Ivar the Boneless I had to do a little research into this story!
Ivar the Boneless was the son of Ragnar Lodbrok, as such he was also known as Ivar Ragnarsson. By the stories that were told, Ivar was everything you would want in a leader – big, strong, wise, generous. But he was also known by reputation as a beserker.
As many people know, beserkers were crazy warriors that went into battle in a rage induced trance like state, although some believe it may have been more drug induced than rage.
What I learned on this drawing – A berserker is often thought of as a bare (berr-) chested warrior, but a more likely translation is that the warriors had a habit of wearing a coat (serkr) of bear (ber-) pelt into battle. Hence the bear pelt Ivar is wearing in my drawing.
As for “the Boneless” part…that’s another story I didn’t have time to dive into. But you can find some information on wikipedia under Ivar the Boneless