Christopher Heyerdahl, who plays the Swede on AMC's Hell on Wheels, talks about finally revealing his character's backstory and his unlikely brotherhood with Cullen Bohannon.

Q: We get a peek into the Swede’s backstory and his history at the Andersonville camp in Episode 508. What was it like to finally portray your character’s past after so long?

A: There’s a terrible loss of humanity that happened to this man in Andersonville, and it was great to be able to incarnate that. It brings me back to the very first episode – the introduction between Bohannon and the Swede where the Swede has a wonderful monologue beautifully written by the Gayton brothers about Andersonville. He shares this story that he would only tell to someone who was going to die. It’s an incredibly intimate story for the Swede to share and he’s not really somebody that opens up. [Laughs] I think that began, in many ways, the betrayal that brings us to 508 and there’s a brotherhood that begins there in the telling of that story – a very unlikely brotherhood between two enemies.

Q: How do you suppose his Andersonville experience shaped him into the man we first meet in Season 1?

A: When we first meet him, we judge him for how he acts, but we don’t know the innocent, playful and undamned young man. Hopefully, while we’re watching the show, you see a man who had great heart and great spirit, but through man’s cruelties became something else. He became the beast that we get to know over the five seasons of Hell on Wheels.

Q: Was that really you playing the harmonica?

A: Yeah, it was. I took lessons and practiced during all the breaks while shooting. Good thing the Swede didn’t play the violin! That would have made me even more hated on set.

Q: John Wirth mentioned welcoming you into the writers room to resolve the Cullen-Swede story. What did you learn during your time in the room?

A: No. 1, I learned something about the generosity of John Wirth. For him to invite Anson [Mount] and myself into the room with the rest of the creative team was an honor. I didn’t really know what my place was there, so I learned to listen and to not hold on. The creative juices flow and some amazing ideas come out. Some of them of course stick, but some are let go of. That happens throughout the season when John and his team are throwing ideas around. It was a great lesson because, as actors, when we hear a great idea, we think “That’s fantastic!” but it may or may not fit in the grand arc of the whole story. Some things fall to the wayside and others spring to life. It was a very interesting opportunity to listen.

Q: Were you surprised that Cullen didn’t kill the Swede when he had the chance to drown him and instead preferred to see him hang? This isn’t the first time Cullen has had a chance...

A: There have been numerous occasions where it could have easily gone the other way. The question that I ask myself, from my perspective, is why the Swede shot Bohannon in the leg and not in the head. I think that’s an interesting question. I think it has to do with the complexity of their relationship, and what Thor Gunderson thinks of Cullen Bohannon and how much he doesn’t want to lose him. I would say the same thing comes up when they’re in the desert at the very end and Cullen, almost on his last breath, is dragging the Swede to – I don’t know – justice, perhaps?

Q: The Swede tells Cullen that torturing an enemy means torturing yourself. What does that mean to the Swede?

A: I think anything we do to others in this life, we do to ourselves. Why is someone an enemy? Why does someone become an enemy? Bohannon became an enemy to Gunderson not out of something he did directly to him as a human being, but something that he did to him as a Southerner. Bohannon represents all Southerners, all the men who took away his humanity in Andersonville, and all the men who created Andersonville and allowed it to flourish in all of its horror. At the same time, I think [Bohannon] knows that he is chasing a ghost. Anything Bohannon does, he does to himself because he has to live with that and survive knowing that any cruelty he hands over to this man, he’s only doing to himself.

Q: The Swede’s last words are “I am Thor Gunderson from Norway.” What did you think about that line considering all the previous personas we’ve seen this man take on?

A: I think the journey that was written in this episode was hopefully a beginning of the joining of two spirits. Bohannon will forever walk away with Thor Gunderson – I wouldn’t say the Swede – as a part of him. The Swede was a false persona and a name that was given to him by a horrible, cruel and dehumanizing man who guarded him and his fellows at Andersonville. He took that name and created an ironic statement on who he had now become. When we come to the end, the final goodbye, he’s saying directly to Bohannon, “This is who I am. No mask.”

Q: Cullen gets emotional as he watches the Swede hang. What did these two men represent for one another?

A: The relationship is very collaborative and stimulating. Whether it’s healthy is another thing. [Laughs] It’s a very stimulating relationship and not one I think can be easily summed up in a sentence or two.

Q: How will you remember your character? Did you think he’d last this long?

A: From the get-go, the character jumped off the page and I saw this man as three-dimensional. There was a heart beating and blood coursing through his veins. He had a history and a future. I’ve been ever-loving, forgiving and protective of that man. That doesn’t always equate to longevity in any series. Many actors become attached to their characters, but receiving this gift of not being killed off in the first season and the final bearing of this man’s soul was a great a journey. It will forever be a part of the patchwork of the quilt of my career.

Read an interview with Anson Mount, who plays Cullen Bohannon.

The final episodes of Hell on Wheels air Saturdays at 9/8c on AMC. To stay up-to-date with all the latest Hell on Wheels news, sign up for the weekly Hell on Wheels Telegraph.