Bjorn Ironside is one of the main characters in Vikings, as well as the eldest son of Ragnar Lothbrok and Lagertha, but the real Bjorn’s life was very different, beginning with his parents. Created by Michael Hirst, Vikings made its debut on History Channel in 2013, and even though it was originally planned to be a miniseries, it was so well-received by critics and viewers that it was quickly renewed for a second season. Vikings lived on for a total of six seasons, with fans currently waiting for the final batch of episodes to arrive.

Vikings initially followed the travels and raids of legendary Norse figure Ragnar Lothbrok (Travis Fimmel) alongside his Viking brothers, among them his real brother, Rollo (Clive Standen). As the series progressed, it shifted its focus to Ragnar’s sons – Bjorn, Ubbe, Hvitserk, Sigurd, and Ivar – and their own journeys, becoming the protagonists and taking over the series after Ragnar’s death in season 4. Although Vikings has followed their personal journeys and struggles, Bjorn and Ivar have been the leads for a while, as well as the main rivals of the story. In Vikings, Bjorn and Ivar are half-brothers, which has contributed a lot to their seemingly neverending rivalry, but in real life, they were actually brothers.

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Although Vikings has done its best to be as historically accurate as possible, the truth is that there isn’t enough evidence of various details about Viking culture and the characters depicted in the series, so the writers and producers have had to take a lot of creative liberties. Unlike other characters in the series, Bjorn is based on a real-life person, and he was a legendary Swedish king and the first ruler of the Munsö dynasty. Bjorn appears in The Saga of Ragnar Lodbrok and Tale of Ragnar’s Sons, which tell more about his adventures, such as he and his brothers leaving Sweden to conquer Zealand, Reidgotaland, Gotland, Öland, and all the minor islands, but there’s also one important piece of information that Vikings ended up changing: Bjorn is the son of Ragnar and Aslaug, not Ragnar and Lagertha.

Bjorn wathes Ubbe and Torvi walk away as their prepare for their baptism ceremony

According to the sagas, Bjorn was the son of Ragnar and Aslaug, and brother to Hvitserk, Ivar (who unlike what the series showed, was older than him), and Sigurd “Snake in the Eye”. In Vikings, however, Bjorn’s parentage was changed and he was made Lagertha’s son and brother of Gyda, who passed away in season 2 due to a plague. Meanwhile, Aslaug was portrayed as the woman who destroyed Ragnar and Lagertha’s family, and who made way for a lot of problems. Ragnar and Aslaug had four kids together, while Bjorn stayed with Lagertha. Although the writers of Vikings haven’t given a reason for changing Bjorn’s parentage, it was most likely made this way for narrative and dramatic purposes, as not only did viewers witness Ragnar and Lagertha’s break-up through Bjorn’s eyes, but this change also gave Bjorn a strong female figure to follow, which was Lagertha.

In terms of narrative, it works best to have Bjorn as Lagertha’s son and not Aslaug’s as this has also contributed to the rivalry between brothers, mostly that between Bjorn and Ivar. However, it’s important to remember that Ragnar’s existence is still unclear, as he’s believed to be an amalgamation of different people, so with that in mind, it’s very possible that Bjorn’s real parents weren’t Ragnar and Aslaug, but what’s for sure is that he is one of the few Vikings characters based on real-life people and he wasn’t Lagertha’s son.

Next: Is Lagertha Based On A Real Character? Vikings' Mythology Explained