DAVID Duchovny has a bit of a reputation when it comes to being interviewed. Words that fly around are "moody", "irritable", "difficult", "great when he's having a good day" and "keeps you on your toes".

So it’s with trepidation that I wait for him to turn up. I entertain myself by wondering if he’ll be an older-looking Fox Mulder, the clean-cut FBI agent with boyish good looks he played in the hit TV series The X-Files for nine years, or the dishevelled, complex, jaded writer Hank Moody; his character in his current hit TV series Californication.

When he finally arrives - 20 minutes late - Duchovny looks like a regular kind of guy; he oozes "casual" in his grey, long-sleeved T-shirt, blue jeans and combed-back hair.

I soon discover he has the same dry, laconic sense of humour and flat, monotone voice of Moody, and - not surprisingly - he resembles an older version of Mulder.

Although he’s here to talk about the much-anticipated second X-Files film, The X-Files: I Want to Believe, it’s impossible to interview Duchovny these days without discussing Californication, which, even though highly successful, has also proved somewhat controversial, thanks in part to its explicit sexual nature.

When the first series aired on Network Ten last year, scenes featuring full-frontal nudity, under-age sex and nuns performing, er, sinful acts proved too much for Holden and Holeproof, which pulled ads from the telecast.

Religious groups were also outraged. However, Duchovny, who this January won his second Golden Globe with the role, is quick to dismiss the furore.

“I heard there were complaints in Australia from people who hadn’t seen the show, but I don’t know what’s explicit about it,” he says. “I’ve seen similar sex scenes on TV for a long time, in The Sopranos and Sex and the City. People like to get upset. They like to have their panties in a twist,” he says, before adding with a wry smile, “I’m here to make you laugh.”

The sex scenes in Californication, the 47-year-old explains further, are more a vehicle for the comedic nature of the show and their inclusion is not primarily to shock the audience.

“Shooting the sex scenes is usually part of the ‘funny’. It’s not porn; we’re not trying to turn anybody on,” insists Duchovny, who is also a producer and a director on the show. “When I approach each sex scene I say, ‘OK so, in this scene, I’m knocked off the bed and I throw up on a painting. How are we going to reach that part where I vomit on a painting? How do we set it up so it makes sense, is real and funny?’ To me, the more real it is, the funnier it is, and the less we try to be sexy, the better it is.”

New York-born Duchovny didn’t intend to become an actor, only taking it up at 27 as a way of making extra cash while he was working on his university thesis (he never finished his PhD on magic and technology).

He scored jobs in beer commercials before landing a brief appearance in the 1988 film Working Girl.

His big break was as a cross-dressing DEA agent in TV’s Twin Peaks, which led to a string of small roles in various films of varying quality, such as Beethoven, Chaplin and Don’t Tell Mom the Babysitter’s Dead. But it was his role in the movie Kalifornia, which starred Juliette Lewis and Brad Pitt, that was to prove pivotal to his career. His supporting performance in the film was spotted by Chris Carter, who was in the throws of looking for someone to play a character called Agent Mulder in The X-Files, a new TV show he was creating.

And so began Duchovny’s ascent to the big time. The X-Files chronicled the adventures of Fox Mulder and Dana Scully (Gillian Anderson), two disparate FBI agents assigned to investigate unsolved cases involving the paranormal, the supernatural and the inexplicable.

It became a worldwide hit, winning numerous awards including Duchovny’s first Golden Globe in 1997.

In Australia, the show’s catchphrases, ‘The truth is out there’, ‘Trust no one’ and ‘I want to believe’ became pop culture touchstones. It was aired successfully in primetime on Network Ten for eight consecutive years.

Clearly, Duchovny was not worried about being typecast, as he did the job for nine seasons and is back for the long-awaited second X-Files movie. (The first film, 1998’s The X-Files: Fight the Future, grossed a respectable $7.5 million in Australia and $85 million in the US.) “I was more worried about not being cast,” he says, laughing. “I wanted a job. I thought, God, will I ever be cast? I think people such as Tom Cruise have strategies, but I’ve always just gone with the flow.” In fact, he admits he’d like to do a handful of X-Files movies. “I see it as a franchise; I like the idea of coming back to the guy. I don’t mind that at all.”

The X-Files TV series eventually ended in 2002, with Mulder being discredited by the FBI and on the run from a possible prison sentence. And even though it’s been six years since Duchovny last played him, it’s obvious he has a soft spot for the character that made him famous. “Mulder’s a guy who’s had a lot of disappointments but, at heart, is a questing young man,” he muses. “He’s more of an everyday guy and less of a comic-book hero, therefore you want to see him change a little bit more. I mean, in the series, the guy failed every week. He was always right and he never won. At heart, he’s a guy who wants to believe.”

Without giving away too much of the plot for the new movie, Duchovny does disclose that, as anyone does over the course of 15 years, Mulder has changed. He admits it took three weeks of shooting before he felt at ease with the older version of his character, and that was only after he had an epiphany that the core essence of the story was still the relationship between Mulder and his sidekick, Scully (again played by Gillian Anderson). “That’s when it started to feel like The X-Files, and that’s when I realised a lot of the show is Mulder and Scully. That was good to realise – it cued me into what the hell I was supposed to be doing.” As for their characters’ relationship in the new film, the story-line is being kept under wraps, known only to top studio executives and the film’s principals. The only thing that can be revealed is that it takes the always-complicated, will-they-won’t-they-get-together relationship between Mulder and Scully in “unexpected directions”.

But even though their onscreen chemistry is there in bucketloads, it’s long been rumoured Duchovny and Anderson aren’t exactly bosom buddies offscreen. Duchovny was once quoted as saying, “I trust her to show up and not waste my time. She does the same. We don’t socialise.” When asked whether that’s still the case, Duchovny, clearly irritated by having to defend a throwaway quote he made years ago, justifies it by saying that spending 14 hours a day, 10 months of the year on a television set “is not something any relationship can withstand. That comment is not a reflection on Gillian. I mean, I’m sick of me. I have to sleep to get rid of myself. After we fell into a groove as performers, four years into it, it was always a pleasure to work together. The chemistry worked and it’s still there.”

When the series ended, so did Duchovny’s box-office mojo, not because he made ‘bad’ choices, or was lost in the vortex of being typecast, but simply because the roles he chose in films such as Connie and Carla, Evolution, The TV Set and Trust The Man weren’t smash-hits, even though he liked his own performances. “There’s no such thing as another The X-Files. In terms of television shows, you can’t get bigger, so you can’t say, ‘Oh, well that wasn’t as big as The X-Files.’ I’ve loved certain things I’ve done in the past five years. I never had the, ‘Gee, I should play a villain and try to win an Independent Spirit Award, or show my ass.’ I just wanted to write, direct and work on other parts. If they don’t have the same profile The X-Files had, then that’s OK. I love writing and directing. I’ll do that until I die.”

Something he’s also eternally passionate about is the state of the planet, which he says he’s “been worried about for a long time”.

He drives an electric car and supports celebrity charities that help the environment. Asked what else he does to help, he says seriously, “I do the small things, such as drink my own urine to recycle,” before quickly clarifying with a smile: “I do not drink my own urine. But I do small things; I recycle and turn off the tap. I also try to instil in my children the idea of not wasting, because we’re wasteful by nature. Kids aren’t born with the idea that leaving a tap on for three hours is wasteful.”

Duchovny has two children, Madelaine, 9, and son Kyd, 6, to his actor-wife of 10 years, Téa Leoni. “I’m a flawed, loving dad; patient, impatient, blind - all the things parents are,” he says. “I’m more the disciplinarian. My kids are very lucky because Téa is really a great mum. She’s genuinely adventurous. I’m more the ‘let’s stay at home and play here’ parent, and she’s the one who says, ‘Let’s go have an adventure; let’s go camping,’ and I’m like, ‘Argh.’”

Duchovny seems to have cracked the code for a successful Hollywood marriage. But he puts it down to luck: “I believe it’s just luck in your choosing of a mate. I think statistics for arranged and non-arranged marriages are the same, so it’s just whether you made a good choice. I mean, anyone can fall in love - which could lead you to believe you’ll stay that way. But it’s after that you really find out if you’re compatible; it’s not because you were full of sh*t that it didn’t work out. I just think we chose wisely, luckily.”