Season 3 of "Vikings" is coming to a close and it appears that Ragnar is getting even more desperate as things are going sour. According to the official synopsis of the season finale, Ragnar will be asking his son Bjorn for a favor that "could change Viking history." 

According to a report by the IBTimes, it is likely that Ragnar will be asking Bjorn to step up and marry Princess Gisla, daughter of the King of Denmark and Princess of Francia. However, as stated by Design Trend, the historical Gisla did not marry Bjorn and instead was wed to Rollo. 

If the show would follow its historical blueprint, then Bjorn may deny his father's request, allowing Rollo to take his place as Gisla's groom. This would also satisfy the prophecy foretold by the Seer in episode 5.

In that episode, the Seer told Rollo, "Oh Rollo. If you truly knew what the gods had in store for you, you would go down and dance naked on the beach. A bear will marry a princess... You will be present at the ceremony." 

It is also speculated that the season 3 finale would see the death of Ragnar. In the previous episode, Ragnar already stated he is a dying man and intends to be baptized as a Christian so that he may reunite with his Christian friend, Athelstan, in Heaven. 

"No Christian king will ever be allowed to rule our world," an unidentified character is heard stating in the finale's trailer, which could be the line foretelling Ragnar's imminent death. 

If this is what the finale has in store for fans of the show, then season 4 may jump forward in time and show Athelstan's son Alfred the Great fighting the sons of Ragnar, all of whom unite to avenge their father's death. 

"Vikings" season 3 episode 10, "The Dead," will air on April 23.