Leonardo DiCaprio: Married to Marty's mob

Leonardo DiCaprio appears to be living the Hollywood dream. His role as lovelorn artist Jack Dawson in the 1997 blockbuster Titanic, which still holds the international box-office record of $1.8bn, assured him a champagne lifestyle, a string of leggy swimwear models on his arm, and unimaginable fame - he was even recognised by native Indians in the Brazilian rain-forest.

The sinking ship offered him a golden life-vest and buoyed his career upon the tidal wave of offers that followed. In many respects, however, he is still trying to live Titanic down.

"Everything happened so quickly," he recalls. "I began to feel engulfed by it. As soon as enough people give you enough compliments and you suddenly have more power than you've ever had in your entire life, it's not so much that you become an arrogant prick, or you become rude to people, but you get a false sense of your own importance. You're treading in dangerous territory when you begin thinking you've actually altered the course of history."

It's a trap he seems to have escaped to some extent. He drives a modest Toyota Hybrid, holds hands with orphans in Mozambique and adds his clout to the fight against global warming. Now just 31, he may have recently plunked down $2.5m for his own paradise island off the coast of Belize, but it is a utopian marine-life preserve - as well as the perfect backdrop for his lady-friends to model their bikinis.

And he has become extremely picky about his film projects. In his 16-year career he has averaged just one film a year. Still cautiously establishing his place in Hollywood, DiCaprio has aligned himself with the director Martin Scorsese, for whom he has starred in Gangs of New York and The Aviator, and their latest project, the star-studded, gritty gangster drama The Departed.

Scorsese's bloody $200m crime fest sees Jack Nicholson head an impressive ensemble cast featuring Matt Damon, Mark Wahlberg, Martin Sheen, Ray Winstone and Alec Baldwin as well as DiCaprio. Basing it on the 2002 Asian crime thriller Infernal Affairs, screenwriter Bill Monahan moved it from Hong Kong to the tough streets of South Boston where DiCaprio's rookie cop infiltrates Jack Nicholson's mob in a dangerous game of cat and mouse.

Both in and out of character, Nicholson put the fear of God into Hollywood's golden boy. "As far as Jack is concerned, we kind of expected the unexpected," says DiCaprio. "For me, there were a number of different scenes where I had no idea what was going to happen. One scene in particular, Jack was talking to Marty and saying he didn't feel he was intimidating enough. The next day I came in and the prop guy told me, 'Be careful. He's got a fire extinguisher and a gun and some matches and a bottle of whiskey'. OK... That sense of fear gave my character a whole new dynamic and it completely altered and shifted the scene in a different direction. Certainly whenever Jack came on set, a whole insane dynamic was thrown in to this mix. It was not only like improvising, you had to reckon with somebody who was truly a force of nature. You had to invent things on the spot to sort of combat what he was throwing at you as an actor, and that makes you understand your character more. He brings that kind of stuff out in you."

Scorsese also earns high praise from DiCaprio. "I suppose my wanting to work with him all started while I was doing This Boy's Life with Robert De Niro. Getting familiar with Robert De Niro's work obviously meant Martin Scorsese's work also. So I became a fan of his work at a very early age. I was fortunate enough to get the opportunity to work with him on Gangs of New York in 2000 and it just continued from there. We have a good time working together and we have similar tastes in the films we like. In preparation for this, Marty had me look at some of the early Cagney gangster movies like The Roaring Twenties, and also Scarface, films like that. I've done a couple of movies with Scorsese now and that's the educational part of working with him. He's like a professor of film. He's constantly referencing films. We would all go home with bags of new DVDs at the end of the day because he would be referring to movies and you would have to admit, 'No I've never seen that obscure Czechoslovakian film from 1912, sorry!' He's brought me to different levels as an actor. I look at him as a mentor really."

The gritty violence that characterises much of Scorsese's work may seem at odds with slender physique and elfin features. Indeed, DiCaprio is an ardent pacifist and opposes violence - unless, of course, he's being paid $20m to portray it on screen. "It's not really familiar to me, that form of immediate violence," he admits. "But that's what you do as an actor. If you can't draw from anything in your own real life, you go and meet people that have done these sorts of things. In my own life, I'm not like the character you see in The Departed whatsoever. I don't normally go and smash people over the head with beer mugs. I have never been in a situation where I'm fearing for my life every waking moment of my existence like my character, Billy, does in this movie. But you try to draw up something from your own life that gave you a similar type of emotion. That's the fun of being an actor, finding those moments.

"For me, part of the process of familiarising myself with my character was going to Boston. I got involved in the Boston sub-culture and met some of the real people that were around during the late 1980s. It was important for me to meet some of the real South Boston characters, and get to know them and hear personal accounts."

As well as having an obvious bond with Scorsese, the actor credits another director for helping him to this enviable career position - the man who gave the 16-year-old DiCaprio a starring role opposite Robert De Niro. "Michael Caton-Jones was probably the most influential person in my career because he was the first director I worked with - on This Boy's Life," he explains "I was completely unfamiliar with the level of commitment you need to have to make a movie and how serious it is. You don't come into this business with the attitude that it's a lot of work. You come in saying 'Oh yeah. I can act. I have that talent...' But Michael was the first one to instill in me that you have to have a work ethic when you do what you do, and then it changed my life."

How his life has changed. Now DiCaprio is very much in the know and in charge of his own production company, Appian Way. He will produce his next four projects, all based on literary works: Kurt Vonnegut's Cat's Cradle; Michael Gladwell's bestseller Blink; Robert Ludlum's The Chancellor Manuscript and Edmund Morris' Pulitzer Prize winner The Rise of Theodore Roosevelt.

But despite his production company, the actor confesses that he has no aspirations to direct. "Acting is a really singular kind of thing - it's constantly focusing on yourself and you only have one person to be responsible for, and that's you," DiCaprio explains. "I look at these directors, sitting in these chairs, operating 50 different departments. And they're responsible for everything. I mean, you hire certain people who are good at their job and do quality work - but to put all these elements together and then factor in how an audience is going to interpret that is something that is so beyond me right now.

"Besides that, I feel like I have a lot more to prove to myself as an actor. I want to keep acting for a while and maybe someday I'll think about directing, but it just seems entirely too stressful, to be honest."

'The Departed' opens nationwide on 6 October