[Warning: This story contains spoilers from Thursday's episode of Vikings, "Promised."]

The body count on any given season of History’s Vikings is expected to be fairly high. After all, this was a time period in which people weren’t long for this world, as they all sought a better place in Valhalla amongst the gods.

That didn’t make the twist in the closing moments of Thursday's episode any less shocking, as Lagertha (Katheryn Winnick) finally made good on her promise of finishing off Kalf (Ben Robson) for betraying her and stealing her earldom. After revealing she was “pregnant” with Kalf’s child and accepting his proposal, she easily slipped the knife into him on the wedding day itself before emerging from her tent surrounding by an army of female warriors ready to help her reclaim her throne.

To break down that integral moment and find out how he felt about Kalf’s swan song, The Hollywood Reporter caught up with Robson, who is currently working on John Wells’ newest series, Animal Kingdom, for TNT.

How did you find out about Kalf’s demise?

I found out just before I went back for season four from the producers. We had a discussion and then my fate was sealed as I returned.

Did you see it coming?

You’re always at the mercy of Michael Hirst’s fingertips as he’s at his computer. I think the second that Lagertha said she would kill me but that we would enjoy each other before then, there was always a strong possibility that it was happening. Anything Lagertha says should be taken very seriously, and it turned out to be true.

Lagertha is such a fan favorite — was Kalf always facing an uphill battle having betrayed her in season three?

Yeah, it was. It’s always going to be difficult not to upset the fans when you’re doing things like that to a fan favorite, especially such a cult icon like Lagertha. I was a fan myself — I was an avid watcher of Vikings before I got the opportunity to jump on it. So I knew exactly how the reaction would be when Kalf’s actions were laid out for me.

Do you think he had redeemed himself by death’s door, or was trying to have Bjorn killed the last straw?

Everything Kalf did was to put himself in a better position. Usurping Lagertha was to gain a position of strength. As he said in season three, he wanted the poets to sing about him in the same vein as Ragnar and to be recognized by the Gods in Valhalla. At that point it was about status. He did it to potentially turn Lagertha’s eye as well. In terms of the whole Bjorn thing, he became culpable by bringing in people like Erlendur (Edvin Endre). Erlendur is still very much wanting to get into a position of power similar to his father and those were the terms of agreement of him bringing his army and his kingdom to work alongside Kalf. I don’t think those actions were necessarily there to hurt Lagertha in any way or form; it was very much about survival and pushing forward. Those things he did, especially in coming back from Paris, were really to try and prove to Lagertha how much he did love her.

Was it a reciprocal love?

Yeah, I think you can see it by the end. There is such a chemistry; it wasn’t a sort of brutal way of being killed, it was very intimate in the way that it was done. It was done on the wedding day within an embrace. There were feelings. To be someone’s second in command and in someone’s private quarters is a very privileged place to be. They knew each other very intimately. She brought him into her world originally in that position. It all only changed when Kalf turned from a boy to a man to a certain extent that he became a much more powerful individual. There was a mutual understanding and love towards each other.

Would you consider his death itself a bit of a feminist movement thanks to the female warriors rising up?

Absolutely. There are many ways to look at it in terms of it always being harder for women getting themselves to the top as opposed to men — there’s obviously a very big discussion in that. You could also see it as a man squashing down a female’s opportunity of power and success and it’s retribution for that and how she felt towards it. I think it’s great how powerful the women are in this series. They’re incredible actors and characters. We’re still talking about a time in Vikings where people didn’t live long and were always looking over their shoulder. It’s going to be a remembered death. It wasn’t on the battlefield; it was about the complicated dynamic between two people and someone who took action in a way that felt necessary during that time period.

How do you predict she’ll rule without him now?

Lagertha is such an incredible character; her arc has been pretty astonishing from the beginning up to this point. Her ruling will be strong and very experienced. She’s been alongside the now King Ragnar and seen how he rose to that position. She understands everything in England with King Ecbert. And she’s been to Paris … she’s very worldly and has an incredible experience, so I would imagine that she’d rule very well. She’s smart and not to be underestimated.

Some past characters have resurfaced in visions and dreams — could that happen with Kalf?

It just depends on where Michael is going with it and if we find out how Lagertha really felt about Kalf after the whole wedding thing. There might be a mourning process into how she feels or there might not be. It’s a relationship in which they’ve known each other a long time, so it’s to be expected.

Vikings airs Thursdays at 10 p.m. ET/PT on History.

What did you think of Kalf’s death? Sound off below.

Twitter: @amber_dowling