Joaquin Phoenix continues career reboot with ‘Her’

Reporters have been conditioned to brace for Joaquin Phoenix. He’s reputed to be volatile, evasive and guarded — an all-around difficult person to interview.

But after Phoenix, with his shoulder-length hair pulled back, strides energetically into a hotel room and begins chain-smoking American Spirits (despite a cold and plans to quit), that reputation — stoked considerably by his fake documentary “I’m Still Here” — quickly disintegrates.

Though the making of that film about his supposed exit from acting (and the infamous David Letterman appearance) was a public-relations debacle for the 37-year-old Phoenix, it also rejuvenated him as an actor: an intentional bid to tear everything down so he could build it back up.

“Once you’ve experienced a thrashing and failure — even if it’s self-imposed — you have a choice: You can let it be the end, or you can fight to come back,” says Phoenix. “To suddenly be in this position where you have to prove yourself again, I thought, was really good and something that I needed.”

Four films later, the reckless experiment appears to have worked remarkably well. Phoenix has responded with the best run of his career.

He’s made two films with Paul Thomas Anderson, having just finished shooting “Inherent Vice,” an adaptation of Thomas Pynchon’s detective novel. The first, “The Master,” in which Phoenix played a restless, feral World War II veteran, was perhaps his best performance ever — the wanderings of a confused, uncontrollable man in postwar America. In James Gray’s not-yet-released but also enthralling “The Immigrant,” he plays a New York man who preys on immigrants coming through Ellis Island.

And now he stars as Theodore Twombly in Spike Jonze’s “Her,” a romance that begins with a futuristic high concept but morphs into a sweet exploration on the nature of love. Twombly, who lives in a sleek, cushy near-future Los Angeles (Jonze used Shanghai’s skyline), falls for his highly intelligent, Siri-like computer operating system, voiced by Scarlett Johansson.

Whereas Phoenix’s Freddie Quell in “The Master” was wild and isolated, Theodore is gentle, open and soulful.

“All of those things exist in me,” says Phoenix.

The multitudes in Phoenix and his quick-shifting moods have made him famously unpredictable. It’s also made him an exceptional actor, one particularly bent on both inhibition and total vulnerability. Talking to him, at least on one recent December day, revealed a warm, affable and playful guy — someone a lot more like Theodore than you’d expect.

“I had this other image of him,” says Jonze. “Some of that — and maybe a lot of that — is because he doesn’t care. He’s not trying to present an image. He’s not trying to sell anything.”

The middle child of five from a transient, bohemian family that settled in California, Phoenix knew from a young age that he loved acting. Like his siblings, he was a child actor, which he recalls as a pure kind of acting. He’s driven to go back to that childlike feeling of fully believing a scene’s reality: “I only want to experience that,” he says.

But the idea that Phoenix, who typically has cast and crew members call him by his character’s name on the set, is obsessed with “staying in the moment” is also a misconception, he says.

“It’s not a science to me and I don’t want it to be,” says Phoenix. “I don’t always know what the right thing is. Sometimes you’re in there and you’re just trying stuff.”

The hurdles for such spontaneity would seem considerable on “Her.” Phoenix spends much of the film alone on the screen, talking with the operating system, named Samantha. The role was originally played by Samantha Morton who was replaced in postproduction by Johansson. During the shoot, Morton was nearby in a sound booth, piped into Phoenix’s ear.

The movie has to balance the oddness and potential creepiness of seeing a man swoon for a disembodied voice (who in one scene he has a kind of sex with). To create a feeling of intimacy, Jonze kept on-set crew to no more than 10 in the first weeks of shooting.

“The best experience for me is when they go ‘cut’ and say, ‘OK, we got it,’” says Phoenix. “And you’re like, We only did three takes.’ And they say, ‘No, we did 13 takes.’”

Phoenix admits he was “panicked” at times during “I’m Still Here”: “If you had seen me, it was not the face of a brave man.” But when asked if his excitement for acting has been reinvigorated, he quickly answers: “Oh, God, yeah.”

It’s one thing Phoenix doesn’t equivocate. Everything else about him is fluid. As the conversation winds down, he puts a disclaimer on thoughts he espouses on the Academy Awards (he’s been nominated three times), which he says — contrary to previous comments he’s made — can be a great benefit to an actor.

“But I don’t know. It just depends on the day,” says Phoenix. “That’s how I’m feeling right now.”