Is Vikings Historically Accurate? What It Gets Right

The sagas themselves are pretty unreliable narratives, adding and subtracting characters and plot devices as needed, and the show holds to this tradition as well. It is highly unlikely that Ragnar's BFF would be an apostate Anglo-Saxon monk, and it's pretty doubtful that Athelstan's bastard child with the Anglo-Saxon princess would be the future King Alfred of Wessex.

In fact, Dr. Godlove added a hearty "ha ha ha" to that notion just to indicate its absurdity.