A ferocious bear; a tortured, groaning, crawling Leonardo DiCaprio; a motor-mouthed and feral Tom Hardy; the immense beauty of the Canadian Rockies as filmed by two-time Oscar-winning cinematographer Emmanuel Lubezki. . . London-born actor Will Poulter had a lot of competition for his screentime in “The Revenant,’’ which opens here on Friday.

Alejandro Gonzalez Iñárritu’s follow-up to last year’s best picture Oscar-winning “Birdman’’ is based on the true story of the legendary frontiersman Hugh Glass (DiCaprio). In the 1820s he barely survived an attack from a grizzly, only to be abandoned by the two men entrusted to protect him. Poulter plays Jim Bridger, one of those two men (Hardy plays the other). Though not a lead role, it is a pivotal one.

Poulter, 22, has already made an impact in films like “The Chronicles of Narnia: The Voyage of the Dawn Treader’’ (2010) and “The Maze Runner (2014)’’ and is acknowledged as one of his generation’s most exciting actors (he won the 2014 BAFTA Rising Star award). Nonetheless, he felt intimidated working with DiCaprio, whom he idolizes.

The turning point in his relationship with DiCaprio — and in his performance — came in a scene in which Glass is being buried alive. Poulter discussed this and other topics while eating a hasty lunch at a Boston hotel.

Q. How did you end up in the Canadian Rockies shooting “The Revenant?’’

A. I sent in a taped audition and I hated it. We were asked not to do a Southern accent, but the language of the script kind of called for it and I felt weird about doing it in what they call Standard American, which is this sweeping impression of what an American accent is. I called my agent and said I want to try again but with the accent because I feel the character is Southern. He said, “Don’t bother, Alejandro wants to meet you.’’ And I thought, oh, shoot; I don’t want him to think that audition was my best. Then I met him in person and saw how sensitive and interesting he is and we formed a great connection. A few days later I found out I got the part, which was a shock. And a huge honor.

Q. Speaking of American accents, how is it that British are better at doing it than vice versa?

A. We have an advantage because we get to watch all the American TV shows. I also watched a lot of westerns, which was especially helpful with this role.

Q. Your countryman Tom Hardy, who plays the evil character John Fitzgerald, also shows off his American accent. It seems his voice is different in every film he’s in. What does he really sound like?

A. I don’t think Tom Hardy has an actual voice of his own. Except maybe the one in “The Dark Knight Rises,’’ as Bane.

Q. Did Leonardo DiCaprio live up to your expectations?

A. He exceeded my expectations. As a professional, I couldn’t have been more pleased. I’d have been heartbroken if I met Leo and he wasn’t the nice guy he turned out to be. He is so collaborative. It was amazing having someone of his ability and experience turning to someone like me and saying, “What do you think about this scene? How do you want to play it?’’ With his responsibility in this movie and the physical punishment he took and with the performance he was building he had every right to just look after himself and have everyone else just augment his performance around him. I’m under no illusions about my part. I’m no more than a side dish.

Q. In what scenes did he prove to be especially helpful?

A. The burying of Hugh Glass scene, when Fitzgerald lies about an impending raid and orders me to leave Glass behind. I recall my head being completely fried because my character is so torn in that scene. I have a loyalty to Glass, who is the closest thing Jim Bridger has to a real father. Plus I promised the captain of our party I’d take care of him. On the other hand, Fitzgerald is senior to me so I should follow his orders. He also says what we’re doing is legal. And then, of course, there’s my own will to survive. So I have all these things going on in my head and I don’t know how to play them all. But Leo was very empathetic with the frustration I was feeling and the confusion I was in. He helped me through it, as did Alejandro and Tom. We rehearsed it all day long but we actually shot it in only 45 minutes to an hour. It was an amazing feeling getting it right.

Q. You and Leonardo DiCaprio have a similar career path. You both started out very young in the business and became increasingly successful. Did you ask him for advice on the perils and rewards of stardom?

A. No, actually. For one thing, there is no guarantee that I am even going to work again. I hope I will and will go on to have a long career. But, who knows?

Interview was edited and condensed. Peter Keough can be reached at petervkeough@gmail.com.