[Warning: The following contains spoilers from Vikings' Season 5 midseason finale. Read at your own risk!]

The midseason finale of Vikings set the stage for a new era in Kattegatt unlike any we've seen before.

In the latest clash between Ivar's (Alex Høgh Andersen) and Lagertha's (Katheryn Winnick) forces — which took the lives of Halfdan (Jasper Pääkkönen) and Astrid (Josefin Asplund) — Ivar finally came out victorious, snatching Kattegatt from the woman who murdered his mother. Forced to go on the run, Lagertha, Bjorn (Alexander Ludwig) and Ubbe (Jordan Patrick Smith) quickly packed up what they could carry and fled their home.

But while many left Kattegatt behind, another returned: the midseason finale left off with Rollo (Clive Standen) en route to his old kingdom, his intentions unknown.

Over in Iceland, Floki (Gustaf Skarsgard) also made a shocking decision after seeing his utopian dream crumble before his eyes when a settler is found dead of a revenge killing. In hopes of preventing any more murder or darkness from infecting his spiritual haven, Floki offered himself as a sacrifice to the stunned members of his settlement.

TV Guide spoke with creator Michael Hirst about what fans can expect when Vikings returns for the back half of Season 5, including Rollo's "unfinished business" in Kattegatt, the fallout from Floki's offer and Lagertha's next moves after that devastating loss.

Lagertha was fully prepared to die that day in battle, so how will she cope with surviving?Michael Hirst: I think it's hard and in the long term, she suffers for what happened in that battle. Without giving anything away, it's not as though she just takes it in her stride and it's another battle. It's been a life change, basically. [She killed] someone she loves and it won't be long before you see how deeply and how profoundly that's affected her.

Now that Lagertha, Bjorn and Ubbe must leave Kattegatt, where will they go and what are their next moves?
Hirst:
They have to go somewhere for safety because they're going to be hunted down. Ivar is not someone to mess with. Their location will change, their lives will change and they have to throw themselves on the mercy of unexpected people. The battle has huge, unintended results.

But I just wanted to talk quickly about the battle itself, because I can't remember ever seeing anything like that on TV or in the movies before — a battle in which it's from different points of view — because I thought all battles must be lived individually and the experience of every warrior and human is going to be unique. And so I had this idea of starting the battle again and again, so we just saw it from these different points of view. We had a great director called Daniel Grou who liked that idea and it's one of my favorite episodes, because I do think that it's true to human experience, that the people in extreme situations, of course, re-live parts of their lives. They have flashbacks, they do things, and I wanted to put that into a Dark Ages story because it's true for them and I think it's true now.

I thought the way that you visualized Halfdan's death was particularly moving and captured the emotions of that moment beautifully.
Hirst: That was very moving, and also Astrid's death I thought was very moving. It was hard. I knew that I was going to kill off some major characters and some of my favorite characters, and that was hard. Initially, when I was thinking about the whole episode, more or less everyone was up for grabs. Many other characters might have died in that battle, but I thought it was important to see that brothers could kill brothers and lovers could kill lovers and so on. A main criteria was actually that I thought the ones who died could probably have foreseen their own deaths or could imagine their own deaths, and it seemed more organic for them. But it was a very emotional episode for me, and I just think it was sort of brilliantly realized.

Harald (Peter Franzén) and Lagertha each had to kill someone whom they really love. How will those deaths hang over them moving forward?
Hirst:
Lagertha suffers very, very substantially from her actions, but not maybe immediately, but certainly down the line. Lagertha's done lots of things that neither you nor I would ever do. She's taken lives with her own hands, she's done a lot of violent things, but I think killing Astrid and her baby was a life changing thing that does have a profound effect down the line. Of course, some brothers couldn't kill other brothers. You know, Ubbe couldn't kill Hvitserk (Marco Ilsø), but Harald could kill his brother. I think that's the difference in human beings. I think that's the difference in human nature. Some people put in that extreme position would be able to do it and other people wouldn't. And I was asking the question of myself, I suppose, and of the audience, if you could do it too. Given that situation, would you have done that or wouldn't you? Because Vikings deals with life and death all the time, these are valid questions that keep being asked in the show.

When Ubbe wasn't able to kill Hvitserk, I think it was very surprising for Hvitserk.
Hirst: It was, absolutely. I think if it was the other way around, Hvitserk probably would have killed Ubbe. But Ubbe is now developing and will develop through the rest of Season 5 as a very major, really interesting, slightly deep character. So I knew that Ubbe wouldn't strike because that was not him, he's too much of a thinker. He's taken over a lot of Ragnar's characteristics, Ubbe, and it's just something I like to explore.

Before the battle, Ivar did say that he believed Hvitserk regretted his decision to side with him. Did that regret only get compounded when he saw that Ubbe, the brother he turned against, loved him enough to not kill him when Ivar, the one he sided with, has repeatedly threatened him?
Hirst:
I think Hvitserk is an interesting character because he's so conflicted and he still doesn't know why he jumped ship and joined Ivar. He knows that he had to do that or that it was something to do with his destiny or his fate, but he still hasn't worked it out. So Ivar kind of teases him constantly and this is a storyline that will continue because both Ivar and Hvitserk must work out what their relationship actually is and why they're fated to be together. So you can't read too much into that one moment. It's part of an ongoing dialogue about Hvitserk — whose side is he on, what does he believe, who is he? He's a free spirit, he's a loose cannon. Everyone else seems to be settling into a role. You could define what they are, more or less, but you can't define Hvitserk yet. And he can't define himself. So all these actions that he does or doesn't do are part of that process to find out who he is.

Floki made a very shocking offer in this episode. What does it say about Floki that he's willing to sacrifice himself for this new settlement?
Hirst:
Floki's desperate now because he wanted to take a lot of godly people to a godly place, just like the puritans, because he believes strongly that everyone has fallen into bad habits and murderous habits and they're selfish and all the bad things about humans. And he took them away somewhere they could start again, they would reform themselves, they would behave well. But this is a big argument about whether human nature or nurture is the thing that defines how you behave. It's just turning into a nightmare for Floki because people are behaving in the way they used to behave back home in Scandinavia and pursuing personal vendettas and all the things that he was trying to get away from. So he makes this dramatic offer to sacrifice himself just in case that would make everyone good and it's unlikely that that would be the result, but it does show that Floki now is in an extreme situation and the whole settlement is in an extreme situation. And what I can tell would not be a surprise, it just gets worse and worse and worse until it becomes unimaginable.

Ivar made a lot of deals with a lot of different people to get to where he is now. How will he manage all of those alliances now that he's the king of Kattegatt?
Hirst:
Ivar has a certain little Trump-like quality. He'd promise anybody anything and he's not worried about the consequences, so if you caught him out in a lie — "you said this, why aren't you doing that?" - he'd say, "I never said that." So Ivar is a force of nature. He's still overcompensating for his childhood and he's persuaded himself that he's the true heir of Ragnar in the sense that Ragnar was a sort of mythic warrior, brilliant guy and a genius, and Ivar is going to be his true heir, a sane genius and all that and be as mythic and as remembered as his father. So he doesn't really care too much what he says. The fact about Ivar is however terrible he is, and whatever terrible things he is, you're still interested in him. He's always fascinating. He's always compulsively watchable.... So this is the big thing about Ivar: that he plays this wonderful game that he can be absolutely awful and horrible and break any promise and do anything he wants, and yet you still feel for him. That's a cute thing, if you can get away with it.

Rollo is on his way back to Kattegatt. What does he aim to achieve on this journey?
Hirst: Rollo has some unfinished business and I knew about this unfinished business even when I was writing Season 1 and I think when it's revealed, most fans of the show will absolutely know what I'm talking about. And it's about Ragnar and Lagertha and all sorts of things to do with his personal life. So he's come back as a huge, powerful successful man, but he can't leave the past behind. Nobody can ever leave the past behind. But he comes back to deal with his own past and he has very, very strong motivations to do so, and it's interesting how that works out. It's very interesting.

Ivar now has some of what he wanted — to be king of Kattegatt - but Lagertha is still alive. Will his ruthless pursuit of Lagertha continue to be one of the main storylines in the back half of the season?
Hirst: Oh my goodness, I can't even begin to go there because it gets so deep and amazing and violent and wonderful. My head is full now because I'm halfway through Season 6, so I'm about 20 episodes ahead of you and I cannot even begin to tell you how emotional and amazing the things that finally happen to Ivar and Lagertha and Bjorn are and the things that are coming down the track. I love these characters so much. I love Lagertha so much... It's a huge joy to write about her. So I don't want to give anything away. But you know, for all the millions of fans of Lagertha around the world, I can just promise that it just delievers and delivers. It's amazing. She's absolutely amazing.

Vikings will return for the back half of Season 5 later this year. History has already renewed the drama for a sixth season.