SPOILER ALERT: Do not read if you have not yet watched “Ragnarok,” the fifth season finale of “Vikings.”

The era of “Vikings” may be coming to an end on History after its upcoming sixth season, but the international co-production still has a ways to go before it goes dark for good. The show’s penultimate run wrapped after a season that reached more than 30 million total viewers and landed in the top 10 in cable dramas among all key demos, including total viewers.

“Ragnarok,” returned the characters to their home base of Kattegat for a blood- and fire-soaked finale when Bjorn (Alexander Ludwig), Ubbe (Jordan Smith) and Hvitserk (Marco Ilso) faced off against their brother Ivar (Alex Hogh Andersen) for the kingship. While things looked dire for Bjorn and co. at the outset, a betrayal from Ivar’s wife Freydis (Alicia Agneson), who was still bitter about Ivar leaving their child behind for the wolves, resulted in Bjorn claiming Ragnar’s throne and Ivar slinking off in disguise.

Here, Variety talks with “Vikings” creator Michael Hirst to talk about Bjorn’s potential struggles as a “liberal” Vikings leader, ending the show, creating the most ambitious season to-date and a potential continuation series.

Bjorn has always been resistant to lead Kattegat, why make a claim to the kingship now?

Kattegat is, in terms of our Vikings world, the spiritual home. Ultimately everything goes back to Kattegat and if you really want to wear the mantle of Ragnar Lothbrok and really succeed in this Vikings world you have to be king of Kattegat. Or queen. There was that great scene with Bjorn and his father on top of that cliff in the mountain, and his father didn’t want to rule. And didn’t like the idea of ruling and thought that it was corrupt. Bjorn feels differently; he feels that he could be a good ruler. I think we’re on the liberal wing of the Viking party. He wants to open Kattegat up to trade and be a much better ruler than Ivar. But there are problems with kingship and Bjorn is a great warrior, but whether he’s a great ruler — and having to deal with complicated and serious political and social issues — that’s another matter. So his spirit drives him back to Kattegat, back to the soul of the Viking world, and then we’ll see in Season 6 how he gets on with that responsibility.

Is it safe to say Bjorn is a better leader than Ivar?

Yes. His instincts are more generous, he’s less crippled emotionally and mentally. He has very good intentions. But the road to hell is paved with good intentions. At the start of Season 6 we’ll see he’s immediately faced with huge questions that don’t have easy answers. If he makes a wrong move or the wrong choices they can lead to very bad results. Just being well-intentioned and essentially a good person, isn’t enough. His goodness is going to be tested when he assumes bigger responsibilities.

Are there any historical power figures you looked at to help script that particular journey?

Not specifically, but I am a history buff and I do a lot of reading of historical figures and periods. Somewhere down the line I have thoughts of Napoleon, particularly. I have thoughts of Hitler or Churchill … But I’m not basing any of my characters specifically on historical characters. I actually start with research and what we know about these real people, even if the details are few and far between. We know that Bjorn went adventuring in the Mediterranean, that he attacked places in Moorish, Spain. He reached the desert. So I can infer from that certain aspects of his life and his psychology. I can build a picture of what I imagine Viking Bjorn would have been. But as we move into Season 6, it’s very important that the other sons of Ragnar Lothbrok all test themselves. They all have a claim to have inherited the mantle of their father. Ragnar Lothbrok is famous in the Viking world and famous and important to the Vikings, so the sons want to be as famous as their father. Bjorn and Ubbe particularly come forward in six to try and play on that mantle. They’re on center stage now with Ivar and it’s very important that they are.

Considering the dream-like quality of the last few minutes of the finale, did you ask Travis Fimmel to return as Ragnar or had you always settled on using the flashback of Ragnar and Bjorn speaking on the cliff?

It’s not really the kind of show where I bring dead people back particularly, so it was always going to be Bjorn’s intense flashback to that very significant moment in his life, when Ragnar tried to tell him things about power. The thing is, whatever someone tells you, the reality is you have to learn these things for yourself. That’s the journey Bjorn is on — and it’s an incredible journey, by the way.

Where does the finale leave Ivar for Season 6?

There have been some comments that Ivar is a little two-dimensional and that he hasn’t got any secrets left, or that he’s not as interesting as Ragnar was. The fact is that we’re going to learn a lot more about Ivar in Season 6. We’re going to see other aspects of his character and things we didn’t expect from him. I’m very pleased with the way his character deepens and changes. He’s still Ivar and he’s still unpredictable and crippled in many ways. But we do see these other aspects in him emerging. Clearly he hasn’t been a very successful ruler. We know the obstacles he’s had to overcome in order to get to the position he gets to. Whatever terrible things he does, somehow you never stop being interested in him. Or having sympathy for him because I keep reminding people where he came from. He is a cripple and he’s been in pain the whole time. His father left him outside to be eaten by wolves. It’s not that I forgive Ivar for what he does but I do understand a lot of things he does. He is capable of changing.

How does Hvitserk fit into the final season?

Hvitserk is an incredible character because to some extent he alludes definition while the others wanted to define themselves as Vikings, great warriors or monumental figures as the sons of the great Ragnar. Hvitserk has fallen through the cracks quite a bit and he’s a very sensitive, troubled person. The main thing in his life has always been why he jumped ship. Why, when he had the choice of staying with Ubbe — the brother he seemed fondest of and who was the most generous — why he suddenly decided to jump ship and join Ivar. It worries him, and at the same time it perplexes Ivar. They both come to feel that the gods mean one of them to kill the other. They’re trying to work that out. That storyline continues to obsess Hvitserk. But he does grow. He grows beyond hope and despair. He develops an identity that’s very mature and different and he stops being such a haunted figure. The process is fascinating but bleak, because before that he has to do — and he does do whether he means it or not — terrible things.

How did you come to the decision to end the show with Season 6?

I always knew where I wanted the show to go and more or less where it would end if I was given the opportunity. What I was trying to do was write the saga of Ragnar Lothbrok and his sons. After six seasons and 89 episodes, that’s what I felt — finally — I’d done. We stopped shooting the final episode in November last year and I felt that I’d said all I needed to say about Ragnar and his sons. I told my saga, and I’d been very fortunate to be given that opportunity by MGM and History. I had no reason to want to continue it beyond that. But, there are 20 new episodes to come. We visit three new worlds in those episodes, we go through great tragedies and great heroism, and if you have tears to weep be prepared to weep them as you watch Season 6. I’m very proud of the show. I did what I wanted to do, that’s the truth.

I don’t want people to think the show is ending anytime soon because it’s not. Later this year we’ll see the first part of Season 6. I’m desperate for people to see it because it is the most ambitious and intensely emotional episodes of “Vikings” ever. Each season I set new challenges for production and they always meet them. Each season I up the ante and they always do it — whatever it is I ask them to do. A lot of what we shoot is real, it’s not CGI, and the way production manages to realize what I put on paper is transcendental. It’s incredible, it’s fantastic. So we have new worlds, new landscapes, new characters… and the scope just seems to be bigger. As are a lot of the issues. We’re on a world stage now with the Vikings, so everything is greater and more significant. And I swear to all the fans. It is a truly, deeply, emotional experience so I look forward to people watching it.

Should viewers watch the final season with a closer eye given that there’s a spinoff potentially coming?

Well, it’s not a spinoff. We’re talking about a continuation series, which I’m still going to be very involved with. Jeb Stuart is the other writer and it is exciting, but my main focus was on my characters. I have to say that they’re not characters to me. I write so much about them, I’ve lived with them for seven years. They’re real people to me. So I care, and have been caring, about them for a long time. I want to guide them through whatever storylines they have. That was my principle objective — to do justice to these incredible characters I found in history and helped to create onscreen. So no. I wasn’t thinking about the future particularly when I was dealing with my people, my characters, my beloved Vikings.

You’re calling this a continuation, not a spinoff — what is the difference?

Continuation means, that if we make it, it will be connected to my saga. It may not involve necessarily the same characters. I can’t go into more details than that, but for the fans of the show it will be a continued enjoyment of the “Vikings” experience.

In the past you’ve mentioned exploring Valhalla, would that factor into the continuation at all?

No, it doesn’t. At some point “Valhalla” became an in-joke with the studio, that I seemed to be killing off so many major characters that I would have to do another show called “Valhalla” and bring back all the people I’d killed off. I don’t think that would work because I tell you what. What was supposed to happen in Valhalla, according to the sagas, was all the dead warriors would feast and drink with the Gods every evening in the hall at Valhalla, and in the morning they’d all enter the great courtyard and fight and kill each other. Then they’d go back inside and feast and drink again. There’s not enough storyline.