Leonardo DiCaprio on Reuniting with Robert De Niro for “Killers ”30 Years After “This Boy's Life: ”'Full Circle'

'Killers of the Flower Moon' marks the third feature-film collaboration between the two actors, after 1993's 'This Boys Life' and 1996's 'Marvin's Room'

Leonardo DiCaprio is reflecting on his 30-year working relationship with Robert De Niro.

The 49-year-old actor appeared Sunday on a panel with his Killers of the Flower Moon costar Lily Gladstone, where he opened up about how, in a sense, the relationship between his and De Niro’s characters mirrors that of their roles in 1993's This Boy’s Life.

"I happened to have done a film [titled] This Boy's Life where I had an abusive stepfather in De Niro. So it was this insanely coincidental, full circle, sort of similar relationship," DiCaprio said during the Q&A session with Gladstone, 37, following a screening of the film in Hollywood, California.

"It felt like I was stepping into the same or a similar character 30 years later, grown up," the Academy Award winner continued. "[De Niro] was still [playing] this abusive character. He was the abusive stepfather."

Of his own character in Killers of the Flower Moon, DiCaprio said, "Developing Ernest was interesting because out of all the stuff that I researched — all his writings, all the testimony, speaking to relatives in Oklahoma — the one resounding consistent element was that this man was quite slow and easily manipulated, that [De Niro's character] Hale had this mental stronghold over him."

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DiCaprio also talked about the "reverence" for the "dual relationship between actor and filmmaker" that he had for De Niro, 80, and director Martin Scorsese when he was growing up in Los Angeles, calling it "on the uppermost tier of echelons for young actors."

"It's all we spoke about in our younger age," the actor continued. "And to be able to have gotten to have my first opportunity working with Mr. De Niro on This Boy’s Life, and then have him refer me to Marty saying, 'Here’s this kid, I just worked with him.' And then having done, what is it, six films with [Scorsese] now? Something like that."

"And then 30 years later now, getting to work with both of them, my two sort of cinematic heroes, and creating this entire story and narrative in these characters was, needless to say, one of the highlights of my entire career and life," he added.

Killers of the Flower Moon marks the first film De Niro and DiCaprio have starred in together for Scorsese, 81. But after This Boy's Life, they also appeared together three years later, in 1996's Marvin's Room.

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DiCaprio went on to discuss how "fascinating" it was to watch the "process" of longtime collaborators De Niro and Scorsese, and to see how "different" their professional dynamic is compared to his own with Scorsese.

"Marty and I have our own sort of relationship. We talk about things in great length, in great detail. We throw things out. [Scorsese and De Niro] have this almost instinctual connection that is almost hard to describe," he explained.

The actor praised Scorsese's effort on one particular Killers of the Flower Moon scene between his and De Niro's characters as "mesmerizing," noting how the filmmaker "wanted it to be as real as possible."

"I've never seen him more completely obsessed with getting to the truth of a story," DiCaprio said. "He so wanted to tell the story correctly. He felt an incredible, incredible responsibility, especially after meeting the Osage community and telling this lost chapter in their history."

Killers of the Flower Moon is now playing in theaters.

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