Having recently won a Golden Globe for his riveting performance in The Revenant,  Leonardo DiCaprio has become an enigma of sorts. There are just a handful of certainties about Leo.

He is 41 years old, a Scorpio and the most bankable male movie star in Hollywood. If DiCaprio says he wants to be in a film, it not only gets made, but it also gets seen; in the past four years, the films in which he has starred (Django Unchained, The Great Gatsby, The Wolf of Wall Street) have made collectively $1.2 billion at the box office. He has been nominated for an Oscar five times (four acting nominations and one for best film, as a producer on The Wolf of Wall Street).

DiCaprio gives off a powerful message that he doesn’t want to talk about anything personal. He is serious, imposing even, sighing heavily and puffing on an e-cigarette as he awaits my questions.

A man of mystery

Based on the performances that have made DiCaprio’s name, one could be forgiven for expecting an entirely different creature: the frivolous charm of Romeo (Romeo + Juliet), Jack Dawson (Titanic) or Jay Gatsby (The Great Gatsby); the verbose shape-shifting of Frank Abagnale Jr (Catch Me If You Can), Howard Hughes (The Aviator) or Jordan Belfort (The Wolf of Wall Street); or the complex vulnerability of Arnie Grape (What’s Eating Gilbert Grape), Danny Archer (Blood Diamond) or Frank Wheeler (Revolutionary Road). In truth, DiCaprio is all of these things and none of them. And that, of course, is his secret.

All those who worked with DiCaprio on The Revenant are unanimous in their praise, not only for his performance but for his commitment to a project that, during the nine months of arduous filming, pushed all of those involved to their physical, spiritual and emotional limits. “Every day was like a bear attack,” says Iñárritu.

DiCaprio, who spends the majority of the film in a state of tortured silence, did many of his own stunts; he was buried in snow, went naked in -5C weather, ate a raw bison liver, slept in an animal carcass and jumped into a frigid river.

When I remind him of something he once said, “Pain is temporary, film is forever”, a slow smile creeps across his face. “Uh huh,” he drawls. “I would say that this film was the epitome of that.”

DiCaprio admits that the filming experience has taken on a dream-like quality, “like a big, beautiful blur”. And yet he is adamant that any suffering that he and his fellow cast and crew members went through was undertaken willingly in pursuit of a higher cause. “We all knew that we were a part of something pretty revolutionary. From the outset, Alejandro had an extraordinary vision: to create a film the likes of which audiences had never seen before. You don’t get those sort of results without going above and beyond the call of duty.”

From one day to the next, cast and crew of The Revenant could not predict what they might be up against. There were also logistical challenges to contend with. Because of Iñárritu and his cinematographer Emmanuel Lubezki’s absolute insistence on working with natural light, filming was restricted to an hour and a half a day, while the rest of the time was spent rehearsing and prepping shots that the director would then refuse to put on film if they weren’t absolutely perfect.

“I get unhappy doing things that I’m not passionate about,” admits DiCaprio. “Because I feel like I’m squandering this incredible gift I’ve been given to finance films. As soon as my name alone was enough to make this happen, I vowed to myself that I was going to work with directors who were changing cinema, doing something important, you know? This goes back to when I was a teenager, feverishly watching movies like Taxi Driver and Apocalypse Now and saying to myself, someday, I’m going to be a part of films like this.”

A support system

A pretty, precocious only child, the young Leonardo had always had, he says, a “strange, almost sickening desire to perform”. In fact, his earliest memory, aged three, is of going to a hippie concert with his Italian-American father, George, and leaping on to the stage to tap-dance for the restless audience who were chanting for the band to come on.

Unable to focus in the schoolroom, DiCaprio flourished in front of an audience. Plus, acting seemed like a golden ticket. “Money was always on my mind when I was growing up,” he has said of his childhood spent in a rough neighbourhood in East Hollywood. His parents, respectively a legal secretary and a distributor of underground comic books, didn’t earn much money. “So I was always wondering how we were going to afford this and that,” he tells me. “Acting seemed to be a shortcut out of the mess.”

From the outset, DiCaprio’s parents did everything they could to facilitate their child’s ambitions. “I’m indebted to them in every single way,” he says, his guard dropping totally, and touchingly, when the subject of his mother and father arises. “They listened to me, you see. They listened to their kid saying, ‘This is what I want to do,’ and they supported me unconditionally; they made me feel that all my dreams were within reach. Now I know a lot of people who have grown up in much better-off families, with much more solid family structures, who haven’t in any way had that level of love in their lives.”

When the 16-year-old DiCaprio told his parents that he wanted to leave school to focus on his career, they supported him. And when, two years later, he beat off several other young hopefuls to land the role of a boy abused by his mum’s volatile boyfriend — as played by his hero, Robert De Niro — in This Boy’s Life, they made sure he knew how lucky he was. When, in 1994, he earned his first Oscar nomination (best supporting actor) for his portrayal of a child with learning difficulties in Lasse Hallström’s What’s Eating Gilbert Grape, they worked hard to stop his head from being turned.

“My dad’s philosophies, particularly, have had a big influence on my career,” he says. A passionate counterculturalist, George has always steered his son towards unusual work. As a breathtakingly beautiful 19-year-old with Hollywood at his feet, DiCaprio didn’t take the obvious commercial route, choosing instead to play a drug addict in The Basketball Diaries and the tortured poet Arthur Rimbaud in Total Eclipse.

After Titanic, DiCaprio consciously didn’t work for two years, turning down commercial projects such as Spider-Man and Star Wars in favour of more left-field, director-lead films like Danny Boyle’s The Beach and Woody Allen’s Celebrity. Never, for one moment, did DiCaprio take his eyes off his ultimate goal: working with Martin Scorsese. When rumours reached him of his cinematic hero’s development of a 19th-century gangster epic called Gangs of New York in 2001, the then 27-year-old moved agents just to get closer to the project.

When DiCaprio talks about his mentor, he leans forward excitedly. “Marty is the great director of our time, who has taught me two crucial things,” he says. “One, it takes a long time and a lot of patience to make a good movie; and two, film is as valid an art form as painting or sculpture. Ultimately, like any artist, I want to make lasting pieces of art; movies that people will look at and appreciate in 50 years’ time.”

In the 13 years since the release of Gangs of New York, the two men have worked together on four further films, The Aviator, The Departed, Shutter Island and The Wolf of Wall Street. “He’s like a silent-film actor,” says Scorsese. “He can flash half a dozen emotions in a matter of seconds, simply by using his eyes.”

During Scorsese’s tutelage, DiCaprio has turned from a beautiful boy into a handsome man. Their sixth collaboration, The Devil In the White City, due to start filming soon, will see DiCaprio taking on the role of HH Holmes, the prolific 19th-century serial killer.

“I’ve been very lucky to have achieved a lot of the things that I dreamt of achieving as a young man,” he says. “But, at the end of the day — and I truly believe this — it is not about achieving great wealth or success. Because they don’t bring happiness ultimately. They really don’t. What matters is whether or not you’ve fulfilled the idea of having led an interesting life, whether you’ve contributed in some way to the world around you.”