I’ve been a big fan of Will Poulter since he played a young filmmaker in the delightful Son of Rambow, and it has been a lot of fun to watch him grow up — and grow as an actor — in We’re the Millers, The Chronicles of Narnia: Voyage of the Dawn Treader, and The Maze Runner. In his new film, he co-stars with Leonardo DiCaprio, Tom Hardy, and Domhnall Gleeson in a fact-based story set in the brutal world of the early American frontier. He appeared in a Washington D.C. theater for a Q&A with me following a screening of the film and the next day we had a chance to talk about making the film in the Canadian wilderness and working with a Brooklyn-based accent coach to play the real-life frontiersman Jim Bridger.

In “Son of Rambow” you played a young boy who was determined to make his own “Rambo” film. Were you really interested in filmmaking back then?

Yes, it was always very interesting, of course performance in general, but as a kid I used to sit in front of the TV, probably a dangerously short distance away and watch black and white movies and cowboy films. Western upon Western upon Western. And that’s kind of how I initially got into it and then like a lot of kids I had this sort of classic upbringing on Disney movies and then I kind of progressed from there. I watched kind of everything and anything and when it came to performing at school I had the same ethos, I just wanted to be part of just as much as possible and sort of copied whatever I could.

What did you learn from this film about the kind of men you were playing, those early American trappers?

I learned that those guys were incredibly tough. Those conditions were very, very inhospitable and not to be taken lightly. The fact that they would survive through the harshest of winters all for the sake of that trade was kind of amazing to me. I mean really, really bewildering and certainly humbling when you look at what I do for living. So besides experiencing newfound temperatures I grew a great appreciation for the outdoors as well. I am very much a city boy and I really don’t get out into the countryside or the wilderness that much at all. There have been a lot of comments about how hard the conditions were but each of us was lucky to be working in such a beautiful part of the world as well, I mean it really was stunning.

Emmanuel Lubezki’s cinematography is stunning with the greatest depth of focus I have ever seen. And he and director Alejandro González Iñárritu insisted on filming only with available light, no artificial lighting of any kind. How did that affect you as an actor?

It was sort of a return to the filming approach of old, this kind of lost art now in a way these days, and we did rely solely on natural elements and didn’t use electricity to light the scenes and we shot all on location. That just improved for us I think the sense of realism, there was no need to suspend disbelief and there was less to act. When we were cold we were cold and when we were tired we were tired and when we were struck by the beauty of the scenery around us we were genuinely struck by the beauty of the scenery around us. There was no need to fake any of that and I think the authenticity of the experience does translate and I think it makes for much more wholesome and ultimately affecting experience of watching the film.

You have said that your character, based on the real-life Jim Bridger, is interesting because he is just coming of age as a man. As I watched it, I thought your character was in many ways the most important because he was the only one who was still trying to decide what his moral code was, and he was watching everyone else to learn what he did and did not want to become.

He is yet to configure his kind of moral compass. I think it’s perhaps quite naïve and kind of a young mindset to assume the right thing, the absolute right thing can be done at all times. What these men around him have learned is that in this scenario in the wilderness it isn’t as simple as right and wrong and actually what you can be driven to do from a moral perspective, what feels innately right has to be reconfigured and redesigned for this context. It’s pretty unrealistic I think to assume that everyone can have a proper burial and we can carry a severely injured man until he passes away gently by natural causes, I think there are tough decisions that require a certain steeliness and a certain mettle that Bridger just doesn’t have yet. He’s having to make decisions and act in situations he’s just not equipped for at that age.”

Did you discuss the moral continuum issues with the rest of the cast?

There were certainly opportunities for discussion. One of the really gratifying things about being on this film set is regardless of how ambitious this was and the truly groundbreaking way that it was shot, regardless of all of the technical and highly ambitious camera work going on around us, we still had a opportunity to make the relationship between the characters and the interchange of dialogue and the emotional message of each scene, the focus. That’s testament to Alejandro as director. So we were all given the opportunity to discuss those things and ensure that we had what we needed to give the performance he wanted to give.

So we did discuss that and we quickly established our relationships with one another. I think we built some great foundations for that in just the friendships we developed off set and then from there we were able to chop and change things accordingly. Even if it wasn’t necessarily recognized or was clear, I think Bridger would have liked to have seen himself as sort of an understudy to Glass and Glass was pretty much a role model for him, his respect for nature, his kind of heightened awareness of the fact that the land was ultimately the natives’ and of native culture, all of this was something that I think Bridger probably aspired to build into his own life. I think it’s recorded that Bridger himself had a relationship with a native woman and had several children so that kind of continuity creates a connection to Glass. And he was a father. Bridger himself didn’t really have much of a father particularly out there in the wilderness. The group of trappers really does become your family. He joined the trapper community when he was 16 years old after his mother passed so it stands to reason that he saw these guys as family figures.

What was the most difficult day of filming?

I think being submerged underwater was a pretty tough day personally. I think for a lot of us it was when we actually stopped filming one day because of a snow blizzard. The camera froze but no humans froze which was good. And I think once the camera freezes up then it is kind of a license for everybody on set to head inside and call it a day. That was a tough day and that meant coming back and reshooting the scene where I am scratching the design into the canteen.

You had a very contemporary urban American accent in “We’re the Millers,” but this one was very different, an Early American from Virginia. Was that difficult?

I worked very closely with an accent coach Michael Howard who was kind of the accent expert for all of us and was on hand. One of the challenges obviously with doing an accent from a time period early in history is that there aren’t recordings. You would never really get the opportunity to hear exactly what you were shooting for. So I guess we sort of hoped we were in the ballpark of what one would imagine to be a early Virginia or in Leo’s case, early Philadelphia for or in Tom’s case, early Texas. But it was surprising to find out how many of the words sounded similar to English.

The filmmaking here was so natural and authentic. How did that compare to the Narnia film, which had so much CGI?

I enjoy the fact that without CGI there is less to invent. The acting challenge is a lot more manageable. The most challenging thing I think I have done in relation to CGI and interacting with CGI was probably fighting a mouse on a ship; that was pretty challenging. A sword fight on a ship with a mouse is pretty tough. But then again I think as actors I think we get excited by the opportunity to stretch ourselves and use our imagination so sometimes CGI is great. I think there is a real art in what Andy Serkis does certainly and even though perhaps I enjoy doing movies with less CGI I would like to experience working on the opposite end of the spectrum and then do something that’s almost entirely CGI. I would love to do some motion capture work just to be able to challenge myself.

What is next for you?

I just finished a film called War Machine with Brad Pitt and was directed by David Michôd and that was an amazing, amazing opportunity. I was lucky enough to play a Marine and represent the Marine Corps which was one of the biggest honors I have ever had. It was a challenge, though. I mean this was a long shoot. It was tough but I feel like after “The Revenant,” I was better prepared for it than I was had I not done “The Revenant.” 2008 Afghanistan shot in Abu Dhabi so the opposite end of the thermometer this time. And we all did boot camp, the toughest five days of my life I think, but I got incredibly close with the guys who I did it with. There were twelve of us in the platoon and we got incredibly close from the experience. I think we recognize that we were just experiencing a drop in the ocean of what Marines actually go through and even just a small taste of the work that they put in and what they go through to become Marines brought us so close so I can’t even imagine if we were going to do the full-fledged and maximum training available, I can’t even imagine how closely would have got or how painful it would have been.