Having embodied an indomitable Spartan warrior, a plucky undercover nazi-hunter, a valiant us marine battling his way across war-torn Europe and, now, a heroic roman soldier taking on marauding Picts in ancient Scotland, you'd expect Michael Fassbender, star of Centurion, to be a man of not easily rattled. Which may well be the case. Still, if you want to put the willies up the actor, just bring up the prospect of impending stardom – a very real prospect given eye-catching roles in, among others, 300, Inglourious Basterds and Band of Brothers, plus the lead role of centurion Quintus Dias – and watch the colour drain from his face.

"That sort of talk makes me nervous," he says, taking a swig of lemonade at the bar, joint not unaccustomed to the odd celeb. "I try not to think about those things, because I know the bottom can fall out at any moment. My aim is to concentrate on the work and let everything else take care of itself."

Right now he is content to enjoy his relative anonymity while filling Empire in on Centurion and its harsh location shoot. "I thought it was great!" he grins. "We shot most of it up in the mountains near Aviemore, which was freezing but beautiful. We'd get into these half-tracks, minimal crew and just the actors who were needed, drive into the mountains and shoot the scenes in the snow." Which sounds great, albeit a little nippy when you're wearing a skirt. "We weren't actually wearing skirts," he insists. "We figured the Romans would've adapted their gear to their environment, so we had tunics and long pants. It was authentic, we weren't just wimping out. And I did one scene where I'm running through the snow, half naked – from the waist up, not the waist down, thank God. That was tough. But, you know, we got back to the hotel at the end of the day, so it wasn't so bad."

Centurion tells the story of the Ninth legion, the Roman army's elite shock troops, and their ill-fated mission to quell a Pict uprising in the wilds of the Scottish Highlands. "The legend is that 15,000 legionnaires went in there, and not one of them came back. That's when the Romans, so the story goes, built Hadrian's Wall and said, 'This is where civilization ends. We're not messing with those bastards again.'"

Given Marshall's track record (Dog Soldiers, The Descent), Centurion follows in the tradition – dark in tone and lavishly violent. "I'm not sure how dark, though. The Ninth get ambushed over the border and there's only handful of soldiers left, fighting for survival. It's basically a thriller, a chase movie. It's Deliverance meets Apocalypto – which is my favourite chase movie of all time. And Centurion does have that kind of Deliverance thing: being out of your depth in an alien land and not respecting the locals. Minus the anal rape scene, of course." Of course. What it does have is some spectacular dust-ups between the Ninth and the Picts, and, as you might expect, lashings of Marshall's trademark blood-letting. "Well," he says, "you know Neil's not gonna make a movie without a few heads getting lopped off."

Like 300, Centurion involved intense physical training for Fassbender, not least in the head-lopping department. "You have to look like you know what you're doing with a sword," he says, "because these guys were taught to fight from the age of six. You have to sell that illusion to the audience. It doesn't come easily to me, but once I get t, it stays with me. I wouldn't fancy getting into a real swordfight, but I'm great with a broom and a dustbin lid."

Born in Heidelberg in 1977, Fassbender grew up in Killarney and although he speaks fluent German, his soft Irish Accent tells you exactly where his roots are. It was in killarney that he first developed a taste for acting, after his dreams of being lead guitarist in aheavy metal band were crushed at the age of 17 by a friend's vastly superior plank-spanking, he consoled himself by enrolling in a series of drama workshops. When those came an end he signed on with a theatre company, a move that lead to a decisive moment in his life – directing and acting in a stage production of Reservoir Dogs at a local nightclub. It proves a roaring success. "I'm still proud of that," he says. "And I learned so much. It taught me that, with enthusiasm, naivety can be a beautiful thing. I threw myself into it. I was only 18 and directing people ten years older than me."

Naturally, he took the opportunity of telling Quentin Tarantino all about it on the set of Basterds. "He loved it," he laughs. "Which was good because we didn't get copyright. I remember going on radio Kerry and in the breaks they were going, 'So, how did you manage to get the rights from Miramax?' I was like, 'Don't mention that.'" If Harvey Weinstein ever got word of the illicit production, his litigious urgings might have been mollified by the fact that all proceeds went to charity. "That was interesting because it was Reservoir Dogs we couldn't find a charity to take our money. In the end we gave it to a girl who needed an eye operation."

From that moment on, says Fassbender, he was committed to an acting career: "I decided it was what I wanted to do and I was determined to be the best I could be at it." His dedication paid off with a string of films, including outstanding turn as IRA hunger-striker Bobby Sands in 2008's Hunger.

Apart from Centurion, Fassbender can be seen as psycho gunslinger Burke in cranked-up Western Jonah Hex, opposite Josh Brolin and John Malkovich. "I didn't know what I was going to do with him, but Michael Wilkinson (costume designer) came up with really cool outfit. I picked out this bowler hat and immediately thought of A Clockwork Orange. So he's a bit of Alex and a bit of Frank Gorshin's Riddler from Batman – with Kerry accent on top."

He is somewhat more forthcoming about his role as Rochester opposite Mia Wasikowska in Cary Fukunaga's adaptation of Jane Eyre. "I was close to doing Wuthering Heights a couple of years ago. And if you don't get Heathcliff, Rochester has got to be second on the list. It's a great role, there are so many layers on him. He's been hurt, and there’s cruelty to him which I'm looking forward to exploring. And Mia is such a great talent; she's going to be a big star."

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