Recently, your humble correspondent has had reason to catch up on both “Vikings” and “House of Cards.” This research has led to one inescapable conclusion: “Vikings” and “House of Cards” are the same show. Consider the facts! Both are about men obsessed with power and legacy, whose balancing acts and manipulation may lead them to catastrophic failure, imprisonment or death. As they both head into their third seasons, we offer this incontrovertible evidence that Kevin Spacey’s Frank Underwood is just Travis Fimmel’sRagnar Lothbrok with fewer tattoos. 1. Both men began on their shows as prominent citizens interested in more, before advancing to a new position of power in Season 2 (Earl on “Vikings” for Ragnar, and Vice President for Frank Underwood on “House of Cards”) and ultimately reaching the highest point of available power in Season 3 (King for Ragnar, President for Frank Underwood), leading many of us to wonder what they can possibly attain in Season 4, assuming galactic emperor is not an option. An inevitable fall from grace? 2. Both men are aided in their quests by steely blonde women just as capable as them, who they perpetually disappoint and neglect. Both Lagertha (Katheryn Winnick) and Claire Underwood (Robin Wright) wield considerable power of their own, and Ragnar and Frank wouldn’t be where they are today without their help. The question of how far these women will go for the powerful men in their lives is constantly open.