Clive Standen, Alexander Ludwig and Travis Fimmel

Ragnar (Travis Fimmel) and Rollo (Clive Standen) might be reunited, but we wish it was under happier circumstances. The Vikings brothers have united against an even bigger enemy than each other: Jarl Borg (Thorbjorn Harr), their former ally who's taken over Kattegat as revenge. But will Ragnar and Rollo be able to work together again after all that's happened?

"I think with those circumstances it doesn't become about the brothers feud anymore," Standen tells TVGuide.com. "It becomes about the feud of Kattegat and the future of their land and the people that live in Kattegat and the surrounding area."

"There's a whole kingdom and the kingdoms at stake. Everyone's lives are at stake when Jarl Borg comes onto the scene," Standen adds.

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But while the stakes might be higher, Ragnar will find himself at a disastrous disadvantage in his second face-off with Jarl Borg. Not only will Ragnar be distracted by watching out for his son Bjorn (Alexander Ludwig), but between all the men lost in the first battle and those who are still in England, Ragnar's forces are severely depleted. 

"There's no warriors left. There's just old men and children left," Standen says. "It's going to have a devastating effect so it's going to bring everyone together. Plus, it's Vikings against Vikings again. They know all their strengths and weaknesses. It's a lot more bloodthirsty. It's a lot more brutal."

This fight will be particularly personal for Rollo, who betrayed Ragnar in favor of Jarl Borg before surrendering when victory was in sights. "I don't think Jarl Borg will ever forgive Rollo for that. And Rollo is hard to read so you never really know what's going on in Rollo's head so I'm sure Rollo's got a few surprises for Jarl Borg as well," Standen says.

The new war will also force Rollo to face a particularly painful part of his past in Floki (Gustaf Skarsgard). After Rollo nearly killed him, the ship maker isn't quite as quick as Ragnar to forgive the shamed brother. "Floki and Rollo have had contention that started off quite early in Season 1 when Rollo was christened and it just escalates ... right up until the climax at the end of the season," Standen teases.

Are you excited to see another Vikings vs. Vikings battle? Should Floki forgive Rollo?

Vikings airs Thursdays at 10/9c on History.