Bishop Heahmund (Jonathan Rhys Meyers) told Lagertha (Katheryn Winnick) he would have to publicly denounce their relationship when they returned to England, but privately, they couldn't be more affectionate.
ET has an exclusive sneak peek at this week's episode of Vikings, in which the pair gets steamy while discussing their plans for Wessex.
"The king has shown courage after all," Lagertha says of King Alfred (Ferdia Walsh-Peelo) in the clip.
"He has, more than I expected," Heahmund concedes, before noting that their work is not done. "I must seek out the others who conspired against him, and conspired against us. Alfred is not safe, despite his courage... I'm almost certain they intend to replace Alfred with Aethelred, but whether Aethelred is part of the conspiracy or not, I've yet to discover."
"I wish I could help," Lagertha says, approaching Heahmund on the bed.
"Even now, the forces of Satan are gathering to strike," he replies. "That is why you are here, to help me fight against the devil."
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ET recently spoke with Vikings creator Michael Hirst, who teased that there might be trouble ahead for Lagertha and Headmund, despite -- or perhaps because of -- their feelings for each other.
"[The Vikings are] in a desperate situation, but at the same time, because there is a relationship between Lagertha and Heahmund, Lagertha is doubly vulnerable. She's in love, and she doesn't really know Heahmund," he said. "She identifies something about him that she sees as similar to herself. There's a kind of kindred spirit there, but she doesn't know him in any deep way, so the results of their journey will inevitably be extremely dramatic, extremely problematic, will lead to many unexpected results."
"There's no way that this can be allowed to be a conventional relationship, so a lot of things are going against it from the start. But they do seem to have this extraordinary, powerful magnetism between them, and I was interested in developing that, and to what extremes that might lead them. Lagertha and Bishop Heahmund are extreme people. And if you're dealing with extreme people, on the battlefield, they're extreme, and maybe in love, they can be extreme too," he added.
Vikings airs Wednesdays at 9 p.m. ET/PT on History. See more on the series in the video below.