Christian Bale says he became a 'weirdo stalker' while researching his Amsterdam role

When it comes to unexpected inspiration, Christian Bale says there's no better source than real people. He almost speaks about them as if he weren't one himself. "I'm fascinated with people," the 48-year-old Oscar winner tells EW. "I don't begin to understand people ever. That's why I think I love doing what I do, because I'm endlessly confused but delighted by them."

Take Amsterdam, his latest movie with director David O. Russell, with whom he worked on The Fighter (landing Bale his Academy Award in 2011) and American Hustle (2013). It's clear from Bale's on-screen physicality — chatty, slightly stooped, inquisitive — that Peter Falk's TV detective Columbo influenced Bale's take on the role of Burt Berendsen, a scarred, glass-eyed war veteran living in 1933 New York City. But Falk wasn't so present in mind. "It really was just looking at literally five minutes of an episode and seeing the body language and whatnot," Bale says. As for the rest, he picked up "a lot of strange behavior following people around on the street."

It works because Amsterdam's Burt is one of these real people. Told in a whirling, decade-skipping style, Russell's plot goes a bit like this: In 1918, Burt is sent off to fight in France, where he meets fellow soldier Harold (John David Washington) and an alluring nurse named Valerie (Margot Robbie), with whom he forms fast, fierce friendships that only become more unbreakable as they recuperate together in Amsterdam. Years later, Burt and Harold are accused of killing the daughter of a wealthy businessman, but before that (or is it after?), we find Burt providing off-the-books medical treatments and reconstructive prosthetics to his fellow ailing veterans home from the war. Burt meets a lot of kooky characters through his practice. The same with Bale and his own craft.

"I remember one time talking on the phone to David and I saw this amazingly interesting guy walking down the street," Bale recalls. "I just became a weirdo stalker following him and studying him. So he's a big influence, whoever he is out there. I don't know his name. He'll never know, either."

The actor also incorporated characteristics of his now-eight-year-old son, Joseph, "certain hand gestures that he has that I just delight in," Bale says.

Then there was an older character Bale dug out from memory. "David and I had actually started talking about doing a project about an art dealer," the actor recalls. "It was right around the American Hustle time. He was a gentleman who had an injury to his face. Then we put that one away, but certainly he came back and influenced [Burt]." Even Bale can't be sure anymore what that scrapped project was specifically. "David has lots of ideas for stories, and we talk about different films and ideas for the future. I believe it was based on someone, but how loosely? I can't remember."

In Bale's defense, it's been quite a while since Russell first approached him about Amsterdam six years ago. The two would meet regularly in Santa Monica over the years. Sometimes they wouldn't talk about the movie at all, choosing instead to chat about music, banking, or the news of the day. "All sorts of things that we love being nerds about," Bale says, "but there's no wasted time with that. It all comes back and informs. I feel like you get a sense of that in this film. The life that you sense off-camera is so rich."

Bale says he has cupboards full of various drafts of the Amsterdam script he's read over the years, some of which subconsciously made its way back into the final cut. Russell invited suggestions from his actors on set as they worked through scenes. Bale remembers delivering a few lines Russell loved that came from those previous drafts. It was just another thread Bale used to stitch together Burt.

Films like Vice, for which Bale packed on the pounds to play former Vice President Dick Cheney, or The Machinist, for which he became frighteningly thin (dropping down to a reported 120 pounds), are more physically transformative in an overt way. But Bale does transform as Burt, from the shrapnel scars that ripple across his body, to the back brace the actor wore constantly to force the kind of stiffness Burt would have from his war wounds.

Perhaps Bale doesn't lump himself in with these "real people" he talks about because he admittedly hates to see himself on screen. He recoils at the thought of looking like Christian Bale in a movie, shaking his hands as if to swat at flies.

"That's not what I aim to do," he tells EW. "But also what I like very much is that David makes lead characters out of roles that most filmmakers would only put as supports. It gives so much freedom as an actor because you're not having to think about playing a leading man. Aren't there certain things that people expect of me by doing that? No, you can just blow all that out of the water and invent anything that you wish."

Amsterdam arrives in theaters Oct. 7.

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