In the world of "Vikings," nothing, not even family, matters when someone seeks great power. 

Season 3 of the History network's series ended with Rollo (Clive Standen) agreeing to a deal with Emperor Charles (Lothaire Bluteau). In the finale, Rollo agreed to help the emperor defend Paris against his brother Ragnar (Travis Fimmel), in exchange for land and the emperor's daughter's hand in marriage. This will cause an epic showdown between the brothers when the show returns for its fourth season. 

Meanwhile, Ragnar faked his own death, and while lying in his coffin, he learned that his former wife, Lagertha (Katheryn Winnick), still loves him, and that Floki killed Ragnar's close friend Athelstan. 

So what's in store for viewers in the show's upcoming season? Aside from the inevitable clash between the brothers, will fans get to see Ragnar and Lagertha together again? And will Floki pay for what he did? 

Speaking to Variety, show creator Michael Hirst said that Floki killing Athelstan will have an effect on his relationship with Ragnar, and viewers may wonder if Ragnar hasn't known this all along. 

"All these things are pertinent to what happens in season four, but certainly it's a big, big issue and it will feature in a very, very important way in season four with hopefully some unexpected results," said Hirst.

As for Lagertha, the show creator said that she will be navigating some "emotional, political, and physical issues" after she confessed to still loving Ragnar, and that the pair's relationship will continue to be unpredictable.

He said, "In a way, whether they like it or not, they're part of each other." 

Lagertha is Ragnar's first wife, but even after their separation, the shield maiden continued to be loyal to the legendary Viking and even fought battles alongside him. 

Meanwhile, fans can expect new faces when the show returns for its fourth season. According to The Hollywood Reporter, three new actors have been added to the cast as series regulars. Peter Franzen will be playing a Scandinavian warrior named King Harald Finehair, Jasper Paakkonen is set to play Finehair's younger brother Halfdan the Black, while Dianne Doan will be playing "a new and unique Chinese character" named Yidu.

"Vikings" returns for its fourth season on History in 2016.