In Season 1 we first meet Jarl Borg when Ragnar agrees to help settle the land dispute between King Horik and Jarl Borg. Jarl quickly manipulates Rollo and turns him against Ragnar and King Horik. In the battle that ensues, Rollo nearly kills Floki does kill Arne.
Season 2 finds Jarl Borg causing more mischief after he raids Kattegat while Ragnar is absent. There is much game play from here on in between Ragnar, Jarl Borg and King Horik but, ultimately, Jarl Borg meets the blood eagle.
(Photo Credit: History Channel, Metro-Goldwyn-Mayer Studios Inc.)