King Arrec is the Storm King who lost the wealthy Riverlands to the ironborn. Arrec was the last Storm King to rule the Riverlands, an area conquered by his ancestors some three hundred years earlier. He lost them to the ironborn led by Harwyn Hardhand. The books do not mention any other house who ruled the Stormlands besides House Durrendon (before the Conquest) so it is likely that Arrec was a member of House Durrendon.