The first time director Jean-Marc Vallee set eyes on Jared Leto on Skype the actor was in drag as Rayon, the fictitious transgender prostitute he would go on to play in Dallas Buyers Club, alongside Matthew McConaughey as the real-life Ron Woodroof.
"He had a wig, a dress, was putting on lipstick and was hitting on me and he was talking with a girl's voice," Vallee recalls, still incredulous.
"When he arrived on the set he got off the plane dressed as a woman, he went to the hotel as a woman, he never got out of the character. He never introduced himself as Jared, never talking with his own voice, even with Matthew. Everyone met him for the first time when he came to the Toronto Festival for the film's world premiere."
Nobody could deny that Leto, now a youthful 43, is beautiful. In fact his usual rock-star demeanour - the long hair, the facial growth he sports as the frontman and creative force behind Thirty Seconds to Mars - usually counters his natural femininity.
After six years away from movies and having established himself as a musician, he felt free to return and do whatever he wanted to in movies. If the former beefcake, Matthew McConaughey could lose 23kg to play the AIDs-suffering Woodroof, Leto could lose weight and transform himself too.
"I knew that Matthew was really pushing himself and was determined to walk down a different path," Leto explains of the film where he would play the ally of Woodroof, a heterosexual man who took on the medical establishment by selling unrecognised AIDs remedies to AIDS victims after his own shock diagnosis in 1986.
"I thought that if Matthew's willing to bet on this, I'm willing to join him," Leto continues. "I knew he'd made a commitment already and was losing weight and of course I'd done that before for Requiem for a Dream and I'd gained weight as well (for Chapter 27 as John Lennon's murderer, Mark David Chapman).
"I thought Matthew was incredible, because I'm sure he doesn't have to work very much. I'm sure he's filthy rich and he can sit back and just enjoy his family. But he really has a desire to say something and to do something great and I respect that."
Leto also took a leaf out of the book of Daniel Day-Lewis, probably his favourite actor. "He went off and made shoes for a few years; I went off touring for five or six years. I love that he's so patient between projects and he takes his time waiting for the right script."
Leto says his creative bent comes from his beloved "hippy" mum, Constance, who is of Cajun ancestry.
"I grew up around a lot of artist's sculptures and painters and performance artists and I think that had a lot of impact on how I view the world and my place in it."
He says his love of music and acting comes from the same place.
"I'm a creative person; I make things and I share them with people. I want to work on movie projects I'm passionate about, but I was so busy with Thirty Seconds to Mars and we had more success than I ever dreamt of."
Acting-wise Dallas Buyers Club has been the highpoint of his career so far. He took his mum as his date to the SAG Awards, where his peers voted him the best supporting actor and he has been nominated in the Academy Awards, where together with fellow SAG winner McConaughey (in the best actor category) the method-loving Leto is the frontrunner.
The pair certainly deserve high accolades for this adventurous long-gestating movie, which was made for less than $US5 million over 27 days and was a labour of love for all involved.
While McConaughey had four months of weight loss to conjure Woodroof's gaunt appearance, Leto had only three weeks to descend to 53kg to portray the AIDS-afflicted Rayon. "I just stopped eating," he admits, noting that he didn't seek out the assistance of doctors.
Wasn't that dangerous?
"Yeah, but a doctor is going to tell you to eat and I'd done it before. The weight loss is interesting because it changes you inside and out. It changes the way you talk, the way you laugh, the way you move your body and that's great. But I was really weak. Incredibly Matthew had a lot of energy. I don't know how he had so much energy."
Vallee, the effusive French Canadian director of C.R.A.Z.Y., The Young Victoria and Cafe de Flore, allowed his actors a lot of leeway.
"I remember very well how the days were hard and I remember the moments with these two actors, these two gorgeous men looking terrifying and just having every emotion so right behind their skin. We never knew what they were going to do next - and not only in a good way, but sometimes in a scary, is-there-security-around way. I was totally inspired."
While the emotional part of the journey was fraught for Leto, donning high heels and waxing his body was also a challenge.
"Being a woman is not easy," notes Leto, "it takes a lot of work. I feel your pain! I had to have every single hair removed. Then there were the heels, size 12. I have to say I was a natural; I picked it up very fast.
"Though what I especially liked about Rayon is that she had a great heart. She was funny and fun and kind and passionate and cared about other people. It's a great thing to live in that skin and to try to bring some of those qualities into my life."
Leto concedes the reaction to his performance has been incredible.
"I've never had such effusive support and praise for anything I've ever done in my life. I had no expectations, having not made a film in six years. I made this little movie then went back traveling the world - and this happens. I can't believe it."