"It wasn't fun to be him because there's something that stays with you, whether you like it or not, the essence of the character," Bardem says. "You change your behavior. There was a moment where I felt a little emotionally detached from people on set, in my day life. This whole thing of being a foreigner, of being on my own, was matched by the fact that I felt (removed). I'm kind of social. But that thing happened, and I wasn't aware of that. Josh was aware of that. He helped me tremendously to take me out of that."
Perhaps the most difficult part of inhabiting Chigurh was the most obvious: that demented schoolboy hairstyle Bardem had to sport for three long months. As anyone who has ever had a disastrous cut knows, it's traumatizing.
"You see yourself, you see the haircut. You don't realize that it's affecting you in a very delicate way, through your own psyche. What happened to me was that after a couple of weeks, I was a little bit -- a little bit -- strange to myself. There was something that was not familiar. It was like, what am I doing here?"
Brolin helped him get back to normal. "He was depressed during the process. The haircut, he felt he wouldn't (have sex) for three months. Full-blown depression. I mean, bad. Didn't like it. Didn't like the way he looked. He'd stay home for hours on end. He wouldn't go out.
"I tried to get him to go out, see a movie. We'd go out, and he'd sing karaoke."
Now all that drama is paying off. Bardem has wrapped the latest Woody Allen project, Vicky Cristina Barcelona, and is on tap to star in Rob Marshall's musical Nine, set to start shooting once the writers' strike is over.
And now that he's riding the wave of critical adoration, Bardem, who comes from a family of actors, wants to take his time and not make any false moves.
"I have certain aims. I've been working since I was 18 years old. I know what I want to do. Sometimes you have to fight for it, and it's not easy. But in the end, you are lucky, because you have the privilege of choosing. You have the privilege, so why not choose? I want to die doing this job."
Being the standout darling this awards season also has left the modest Bardem, who still hasn't mastered the art of red-carpet banter, feeling overwhelmed.
"This moment is really kind of surprising. Very rewarding, especially the Screen Actors Guild. That's one of the most precious things I've ever gotten. It's a great honor. You celebrate it, and you forget about it. You can't put it on your back. It's an awful weight."
Bardem grins. "And it's a really heavy statue."