One theme running throughout W is that of Luck. Luck meant something quite different to Vikings, compared to how we lucky modern folks think of that word. Rather than luck being something that is imposed on us by outside forces — getting a lucky break or having a run of bad luck in Vegas — for Vikings, luck was an interior quality possessed by a person, similar to a personality trait or a genetic predisposition. Here is a good research article on the Viking conception of Luck.
This little guy plays an important role in our story: