Tom Hardy is a chameleon in the purest sense of the word and it’s his ability to transform himself for roles that means he’s not instantly recognisable.

As a complex and enigmatic figure (think a young Marlon Brando) it’s hard to know what to expect when you meet him in person.

He’s intense, that’s for sure. Physically impressive too, having pumped himself up to monstrous proportions to play the chemically enhanced villain Bane in Christopher Nolan’s new Batman movie The Dark Knight Rises.

Coupled with his shaven head and dark, shark-like eyes, he makes for an imposing figure, even though he’s dressed smartly in a grey shirt and trousers.

His new film Warrior tells the tale of two estranged brothers, ex-marine Tommy (Hardy) and ex-fighter-turned-teacher Brendan (Joel Edgerton) who, for differing reasons, train to take part in Sparta, the biggest winner-takes-all event in mixed martial arts history.

It’s an anthem for redemption and the power of the human spirit.

“The fighting is actually the backdrop to a movie about the struggle of a family trying to find a voice,” says Hardy, aged 34.

By his own admission, “it wasn’t a traditional audition” for Warrior. While he was confident in the dramatic essence of Tommy, he had fierce doubts over whether he could create a fully rounded character and wanted to talk it through with the director and writer Gavin O’Connor.

“He showed up at my house at midnight one Sunday, unannounced. Just a knock on the door,” American O’Connor recounts.

“He was supposed to go to a hotel, but instead stayed at my house for five days. He never left, so I got to know him very well. And the qualities he has as a human being are just right for the character.”

And while Tommy has some unbelievable and often unpleasant traits, his core goodness and vulnerability is ever-apparent, which is testament to Hardy’s skill.

“I know what frightens me and I have a compassion for erratic behaviour that doesn’t always manifest itself in violence,” he says.

“Within the creative arts, you can create or destroy. Passion does both of these things.”

Like all his roles, Hardy threw himself into preparing physically but the shoot proved tougher than he could have expected. He suffered two broken ribs, a broken toe and torn ligaments in his right hand.

The training regime consisted of eating six small meals a day and working out for eight hours (a combination of Mai Tai, Jujitsu, boxing, choreography and weightlifting), six days a week for ten weeks, before the shoot began.

“I bitched, moaned, whined and cried my way though the training, but there is something really invigorating about being punched in the face,” he laughs. “There’s my boy over there,” he says pointing to the equally imposing figure of a man called Pnut. “He’s my spiritual counsellor, a mixed martial artist, my best friend and godfather to my son [Louis, 3, with former partner Rachael Speed].”

Hardy and Pnut now train together every day with Hardy noting that painful as the preparation for Warrior was, at least it was sensible, as opposed to the “naughty” approach he took to play the infamously violent convict Charles Bronson in 2008’s Bronson.

“Then, I just ate chocolate and pizza and carried Pnut up and downstairs,” he says, laughing.

At 19, Hardy entered and won The Big Breakfast’s Find Me A Supermodel competition, which led to a short-lived career as a model and then he “fell into acting”, he says.

He was offered a role in the TV series Band Of Brothers, followed by Ridley Scott’s Black Hawk Down.

On the surface, he was winning, but a drink and drugs addiction was spiralling out of control: “I would black out and wake up in all sorts of places,” he says. After one particular night in LA he woke up “with a dude and a gun, naked,” Hardy continues.

His wake-up call was finding himself battered and bruised on London’s Old Compton Street without any recollection of what had happened. He’s now been sober for eight years.

And life is good. He’s engaged to the actress Charlotte Riley, whom he worked with on TV’s Wuthering Heights.

As well as Warrior, he’s starring in the spy thriller Tinker Tailor Soldier Spy and next year’s The Dark Knight Rises is sure to cement his movie star status.