He is uneasy with anyone not his own age. Which is why 32-year-old director M Night Shyamalan had no trouble talking him into playing Mel Gibson's melancholic younger brother in Signs. A psychological thriller about mysterious crop circles, it has -- like Shyamalan's previous two movies The Sixth Sense and Unbreakable -- topped the US box-office charts, this time with a record opening weekend gross of more than $60 million. 'It was neat having someone who was contemporary telling me what to do,' says Phoenix. 'We were able to talk like young guys. He's -- um -- very precise. He'd written the script, so he understood the characters. I could ask him things and he had the answers.'
We're sitting in an air-conditioned room in the Regency Hotel in New York. It's a sweltering 90 degrees outside on Park Avenue. In the Bronx or Harlem, neighbourhood kids would be cooling off with the water hydrants. Here in midtown Manhattan, everyone is wearing lightweight designer suits. Phoenix has walked over here from his apartment. His shirt is moist under the armpits.
He doesn't like interviews. One reason is that he always has to field questions about his elder brother River Phoenix, who fatally overdosed on cocaine and heroin at the Viper Club in Los Angeles, on October 31, 1993. Ambulances responding to Joaquin's desperate 911 call were too late to save him.
'I've nothing to say about that that I'd want to be public,' he says. Press him on it, and he says: 'You don't understand me?'
His relationship with River and their three sisters Rain, Liberty and Summer seems to have been the only sure thing in his life. He never had a real home. His hippy parents Arlyn Dunetz (who renamed herself Heart) and songwriter John Lee Bottom were always on the move. 'They were of a generation that was searching, that was discontented,' he says.
River was born in Oregon, Rain in Texas, Joaquin (pronounced Whaa-keen) in Puerto Rico and Liberty in Venezuela. By the time the youngest, Summer, arrived in 1978 they were down and out in Florida. They made their way to Hollywood in a battered station wagon, the idea being that the children would provide income by appearing in commercials. 'We'd been singing in the streets of Westwood, much as we had at children's hospitals and in jails and things like that back in Central America,' says Phoenix.
To make themselves more marketable, the family changed their name from Bottom to Phoenix. Arlyn got work as a secretary to a casting director at NBC, and through her the children found an agent. It didn't help that they were vegans and refused any work for Coca-Cola or McDonald's ('nothing dealing with meat or milk or anything like that').
River made the breakthrough first, becoming a regular in the TV series Seven Brides For Seven Brothers. Then he got star billing in Stand By Me, Running On Empty and Indiana Jones And The Last Crusade. 'He kind of led and the rest of us followed,' says Joaquin, who landed his first part in Seven Brides For Seven Brothers, having changed his name from Joaquin to Leaf.
When his parents separated, Leaf took off with his dad to Mexico. 'I learned to speak Spanish,' he says. 'I got to the point where I was pretty good.' He changed his name back to Joaquin, because when he tried to say the Spanish word for Leaf (hoja), people mistook it for garlic (ajo) or eye (ojo). 'I still understand some Spanish,' he says, 'but I'm out of practice.'
With his black hair, green eyes, long eyelashes and deathly pale skin, Phoenix was a natural as Diane Weist's surly delinquent son in Parenthood. The birth-scar on his upper lip made him particularly good at sneering in contempt. When he appeared in the thriller U-Turn, director Oliver Stone accentuated the effect by giving him a rebel-without-a-cause quiff. But James Dean he's not. He typifies instead the white-trash no-hoper: for example in Gus Van Sant's satire To Die For, where he plays the pawn for Nicole Kidman's ambitious local weather-girl .
'What happens is that if a movie is successful and the character is successful, you get 20 scripts that basically are the same character,' says Phoenix. He sensibly set about softening his image, playing a boy from the wrong side of the tracks who falls for rich girl Liv Tyler in Pat O'Connor's coming-of-age romance, Inventing The Abbotts.
There was romance off-screen as well. Tyler remembers thinking Phoenix looked like Luke Skywalker when she was an eight-year-old and saw him in his first movie, SpaceCamp. She claims she swooned when O'Connor cast Phoenix as her boyfriend. They had plenty in common, sharing a bohemian background, but the relationship didn't last.
All the same, Tyler encouraged him to go for more demanding roles. He came across James Gray's The Yards -- a dark expos of city hall corruption in the New York railways -- in the middle of piles of scripts she had in their apartment. Gray came to New York and met with him. 'With virtually every movie I did up until Buffalo Soldiers [which premiered at this year's Edinburgh Film Festival] I was not the first choice,' he says. 'I don't think I was even the 900th choice. And so I'm accustomed in some ways to convincing people I have a feel for a character.'
He convinced Gray to cast him as Willie Gutierrez, who gets rich as a fixer for James Caan, even making it with his daughter Charlize Theron, only to see it fall apart. 'For me it's always the script and the character,' says Phoenix. 'Am I going to wake up every day for four months and still be inspired? Is there enough to explore? Is it the kind of director who's going to work with me and find more about the character than might be there?'
It's an approach that's seen him grow as an actor. In Return To Paradise, he co-starred as a backpacker caught with drugs and sentenced to death in Malaysia; then Philip Kaufman cast him in Quills as the tortured priest who acts as jailer to the Marquis De Sade. 'I dislike scripts that aren't complex,' he says. 'I look for films that take on issues or are willing to dive into areas that are not normally explored in film.'
Ridley Scott's Gladiator -- in which he imparts twisted verve to the character of the power-crazed Roman emperor -- is merely the most prominent example of his particular gift for damaged but charismatic anti-heroes. Buffalo Soldiers, a dark, military comedy set in Berlin as the wall comes down, has been criticised as anti- American. 'It's a period film about a particular time,' says Phoenix. 'It's not an attack on the American military. It's all based on factual events. I don't see why we should fear it.'
He's never fully satisfied with his work. 'If I was certain about what I was doing, I'd probably quit,' he says. 'It would take all the fun out of it. The risk is kind of what drives me and keeps it interesting. I always feel like I haven't altogether gotten whatever role I'm playing. I keep going after roles because I want to be perfect. I want for once to do a perfect job.'
But it could be that this fear of failing is what gives Phoenix's performances their edge. 'He brings an incredible level of intensity and inner strength and an introspective quality to a part,' says Sam Mercer, producer of Signs. 'And so much of his performance is not just verbal, but in the way he carries himself.'
This was evident from his first day on Signs. They were shooting a scene in which Gibson and Phoenix discuss running out of their farmhouse to scare off whoever -- or whatever -- is outside. It's the first indication they've had that the crop circles appearing in their cornfields might be the work of malevolent aliens. 'The first scene we shoot in a movie is always the most nerve-wracking for me,' says Phoenix. 'In this particular scene, there was quite a lot of dialogue. Night was shooting it all in one shot. You couldn't mess up. We'd got all the way to the end. We were nearly done with the scene. And I was thinking: What's that last line? What's that last line? Don't screw it up! And I did.
'There are days when I go home from the set, and for hours before I go asleep I think: 'F***, why didn't I do it differently? Why couldn't I have found it?' There've been times when I've thought they'll cut my scene because it's so bad. And then I see it in the movie, and it's, like, one of my better scenes. So I can't trust myself. Well, that's great.'
For his part, Shyamalan says Phoenix could be one of the great stars if he wanted. But it seems he doesn't. 'Yeah,' he admits. 'That's true. I just want to be me. People define you in terms of other people. Do you want Al Pacino's career? Do you want Chris Rock's career? I want my own career. I have my own ideas.'
Outside the Regency, he lights a cigarette. I ask him: is acting a way of finding himself? 'You can't help but learn about yourself with each experience. But I can't give you specifics. Or if I could,' he adds slyly, 'I probably wouldn't.'
Signs is released September 13. Buffalo Soldiers is released on October 11