You don't go into an Ashton Kutcher interview expecting him to be interesting. This, after all, is a man who found fame thanks to emphatic use of the word "dude".
So when a 15-minute "hi Ashton, please regurgitate your publicity soundbites" exercise turns into a lively discussion about technology, privacy and the inner life of Steve Jobs, we're both taken by surprise.
Here we are in a hotel room in Paris where he's spruiking his latest film, in which Kutcher plays Jobs and carries a painfully creaky script with the pure force of his ability to inhabit a character (itself an unexpected twist). And judging by the way he keeps extending the allotted time for the interview with nods to an anxious PR flack (until I manage to really annoy him - more on which later), he wasn't expecting this either.
Kutcher's CV would emphasise "charming" and "cheeky" among his bankable talents. It would add "Twitter pioneer", "has a hot girlfriend" and "quite good looking in a boyish, pointy-faced way" to his brand. "Rarely asked to demonstrate any serious dramatic acting ability" would be taken as read.
But at age 35, Kutcher's goofy slacker persona is starting to chafe - on him and us. So, is there anything substantial underneath?
Maybe there is. "New Ashton" got a public outing last weekend at, of all places, the Teen Choice Awards. "I feel like a fraud," he told the bemused audience who were waiting for a world-record-setting mass "twerk" (don't look it up).
He revealed his first name was really Chris, and announced that he would share three "really amazing things" that Chris had learnt.
The sexiest thing in the world was being smart, thoughtful and generous, he said. And you should build your life, not just live in it.
"I believe that opportunity looks a lot like hard work. When I was 13 I had my first job with my dad carrying shingles up to the roof, and then I got a job washing dishes at a restaurant, and then I got a job in a grocery store deli, and then I got a job in a factory sweeping Cheerios dust off the ground. And I've never had a job in my life that I was better than."
Kutcher's earnest tone, as if he were giving a graduation speech, sat as comfortably in the Teen Choice Awards as if Dame Helen Mirren had twerked at the Oscars. Afterwards, some pointed out its similarity to Steve Jobs' famous "commencement" address at Stanford in 2005.
It's almost certainly no coincidence. Kutcher has, it seems, chosen a dead mentor to lead him into delayed adulthood. Too old for toxic rom-coms, and stuck in a mindless prison made of cash called Two and a Half Men, but blessed with the advantage that he has a low hurdle to jump to exceed people's expectations, he has found a project that could save his soul: a Steve Jobs biopic.
Kutcher admits that he was lucky to get the role. Jobs is not the only biopic on the go: there's another scripted by Aaron Sorkin on the way. "You know, if it's Aaron Sorkin and some fancy director they probably would never have cast me to play the role," he says. But this one was a quirky project: funded by a Dallas-based company that produces newsletters about the mortgage industry, scripted by its "director of marketing content" and directed by an indy director on only his second project.
Kutcher didn't need this movie to pay the bills, he just needed a chance to show he was capable of something more. And he threw himself into it. It was never going to be enough that Kutcher bears a striking physical similarity to the young Jobs. In the three months before shooting, he lived and breathed the man.
"This is the first time where I've ever had the liberty to actually have time to prepare for a role like that," he says. "At first I just read everything I could find about him and then, thankfully, there's hundreds of hours of footage of him online that you can watch."
He found an online audio library of Steve Jobs speeches. "I just scoured it and compiled them and had like a 24-hour loop of audio files playing in my car and when I went to bed at night I would just listen to him talk." Next Kutcher started chatting to people. He's an occasional investor in Silicon Valley start-ups and knows a lot of people who were friends with or worked for Jobs. Kutcher collected stories, anecdotes, "trying to understand the emotionality of the guy".
"And then I started reading the books that he read and listening to the music that he listened to and wearing the shoes that he wore."
When he met the director, he would spend the whole time in character. He suggested script changes to flesh out Jobs' motivation, or add insight to problems at Apple. He would rewrite lines "to make sure that the words ... were being said the way that Steve would say the words". He would even go off on "rants" in character that the director and writer used for script rewrites.
Even during filming he allowed himself to channel Jobs. At one point during what he called "a wild take" that was used in the finished film, he improvised a line accusing his girlfriend of becoming pregnant to another man. It was based on research, but came out of his deep dive into the character.
He still gets passionate about certain scenes, even after seeing them dozens of times. In one particularly sweary part of our interview, he gets stuck into a former Apple employee who "felt all of a sudden justified to get stock, right? Like, shit like that really bothers me. I'm like, f--- that."
Kutcher says he saw something in Jobs that he could relate to: "He was a performer." As Kutcher's research uncovered, Jobs was a genial magician on stage, a silicon saint who could imbue lumps of plastic and glass with almost supernatural powers - but behind the scenes, he was an uncompromising, infuriating, dictatorial, sometimes sadistic perfectionist.
Even Kutcher can't convincingly defend the guy. "As long as you didn't take things personally, I think he was probably not bad to work for," he offers.
But even then he has (unspoken, but obvious) sympathy. The curse of celebrity is to be judged not on your work, your results, but on your personality and your private life. Technology has made everything worse.
"We're all living in a casino," is how Kutcher describes it. "It's just Vegas. Everything is on camera. Everything is being recorded. Everything is on audio. The truth is we all have access to everybody else's information."
For celebrities, under the gaze of what Kutcher calls "all the sort of magazine, press, shit media coverage stuff" this is the case times 100. Kutcher says his "pat answer for years" has been: when you know someone could always be watching, then you try to behave better.
"But people f--- up. I mean, we all f--- up, we all make mistakes, and we all do stupid stuff. Nobody's exempt, Steve Jobs included, right?
"Everybody likes to hold up a really big righteous sword when people make mistakes. Well guess what, now it's recorded and everyone has access to it ... so let's stop judging people. That's the biggest thing that I think will come of it."
He's almost shouting now.
"You know, you watch these political debates today and you're like, nobody can run for office! Who can run for office? Nobody! Because the one mistake that you made, wherever you did it in your life, is going to have like WAH WAH WAH [klaxons] and who the f--- wants that? What intelligent human being wants that?"
It's clear he doesn't. He doesn't want to dwell on his failed marriage to Demi Moore or revisit Punk'd or talk about Twitter controversies or be voted TV's sexiest man by people too young to have sex with him.
Or rather, it's clear once I review the interview, later. It wasn't clear at the time, because I then ask about his love life. He's recently started dating That 70s Show co-star Mila Kunis. There are engagement rumours. True?
Kutcher slumps in his seat.
"Oh that's a really shitty question. You ruined an awesome interview with a bad question at the end."
Right, so this is the end of the interview, then.
"I don't talk about that stuff man. Cheers. Take it easy."
He's not even looking at me. Maybe he's thinking: "Dude, I've just done what I consider my best work, portraying one of recent history's most fascinating characters, right? And still you're asking me about my goddamned love life?"
Jobs opens in Australia on August 29.