Find out where Floki will be by time midseason rolls around Vikings Floki will pay dearly for the murder of Athelstan, but will Ragnar's vengeance rob the warrior of his life? 'Vikings' Season 4: Bjorn To Kill Rollo? Alexander Ludwig Teases Revenge Kattegat's boatwright made quick work of Ragnar's (Travis Fimmel) closest confidant in season, and when season 4 begins, Floki (Gustaf Skarsgård) will have to pay for his crimes.