Even though Christian Grey is fully naked for most of E.L. James’ mega-bestseller “Fifty Shades of Grey,” moviegoers may be disappointed to learn that star Jamie Dornan won’t be.

“They were privy to everything, just not my manhood,” Dornan says on a recent afternoon in Los Angeles. To portray the sexually dominant Grey, Dornan donned a flesh-colored pouch while filming the love scenes. “It’s like one of those little satchels that Robin Hood or someone of that era would have tied on to his belt,” says the 32-year-old Irish actor. “There’s no back. It’s tiny. I mean, it’s not tiny! Because it’s got to hold a lot.”

The success of “Fifty Shades,” with a budget of $40 million, will largely depend on Dornan, best known for playing a serial killer in BBC series “The Fall.” The actor thinks that Hollywood’s shyness about sex is strange. “In a funny way, the movies as a business are all about sex,” he says lounging on the outdoor patio of the Chateau Marmont on Golden Globes weekend, feeling hung over — and hoarse — from a late night of partying. “It’s an industry built on sex appeal,” he adds, demonstrating this assessment during his photo shoot, during which he kicks off his shoes and spreads his legs on a bed.

Dornan saw a rough cut of the movie just before the start of the Christmas holidays. “This kind of sex — S&M — hasn’t been depicted on the bigscreen ever,” he maintains. “That, in itself, is groundbreaking.”

Dornan crammed for “Fifty Shades” by reading all three books and watching films like “The Thomas Crown Affair” and “American Psycho.” He also met with an expert. “We had an adviser in the field that we’d talk to, a guy on the kink scene,” the actor explains. “He’s a guru, and a dominant. We had some good chats with him. And then there was the practical side of things. How do you use this? I’ve never held that! I learned all sorts of tricks that will support me through my life.”

He wasn’t able to master every prop easily. “There’s probably a technique to using a whip,” Dornan says. “I wasn’t talented at it. But I got there in the end. It’s really like fly fishing,” he says with a laugh. Taylor-Johnson tried to help. “Jamie, how can you make something so straightforward so hard?” she recalls asking him. “Why would you pick (the whip) up like that?” She reports there were minimal injuries on the Vancouver shoot — which took 9½ weeks, of course. “I think there was a bit of rope burn,” the director says. “I’d have to remind Jamie to hold back with the crop.”

Dornan grew up in a middle-class family in Northern Ireland, the youngest of three children. When he was 16, his mom died. “That was awful, and it still sticks with me every day,” Dornan says. “My mom was a glamorous woman, and she would have loved the idea that I’m in the movies.” Dornan started his career as a fashion model a career in which, he says, “I absolutely never had a desire to be.” He transitioned into acting in his mid-20s, when he’d visit Los Angeles with British mates Andrew Garfield and Eddie Redmayne. “We ended up staying in the canyons, renting a place together and helping each other on auditions,” Redmayne says. “We’ve been at it a while. It’s wonderful when people who you’ve seen give it the rigor manage to get that moment.”

Dornan had already impressed Universal executives with an early audition tape he had sent the studio, in which he reinterpreted an iconic scene from “True Romance” where Christian Slater meets Patricia Arquette in a theater. “You have a strong idea in your head of how famous those performances were,” Dornan says. “You’re just trying to get away from that.”

Dornan recalls he was the last to audition that afternoon, and he envisioned Christian as a fantasy. “I almost saw him as a superhero,” the actor says. “People like him don’t exist.” He and Johnson performed two scenes together, the one where Christian meets Anastasia for the first time in his office, and an emotional scene that closes the first book. Dornan flew home to London, where he was instructed to wait for a call, and he passed the time by binge-watching reality series “Storage Wars.” “It was late,” Dornan says. “It was 2:30 a.m. and I was tired. I was like, I just might wake up to the news. But eventually, Sam called me herself.”

A month after he landed the role, Dornan and his wife, Amelia Warner (eight months pregnant), moved to Vancouver for pre-production. He started a strict three-hour-a-day workout routine with a trainer, but struggled to pile on weight. He’d previously injured his shoulder in a skiing accident: “I end up in a helicopter, morphined up, flying out of the Alps,” he says. “We had realistic expectations that I’m not going to look like Chris Hemsworth in four weeks, nor did we feel I needed to. Christian is not some monster. He’s not a beast.” Dornan devoured ham and eggs for breakfast, and he chugged protein shakes five times a day. “I’d set my alarm at 4 a.m., and have one pre-made by my bed,” Dornan says. “I’d wake up in the middle of the night and drink a chocolate milkshake. My wife wasn’t too pleased about that.” He maintained six-pack abs via core excercises, despite his disinterest in sit-ups. “It’s not really my thing,” he says.

Dornan was also relieved he didn’t need to wax his body. “I don’t have a great deal of chest hair,” he says, pulling down his shirt to reveal a few stray tufts. He had to shave his face daily to keep up Christian’s clean-cut appearance. “I don’t like shaving,” he says, pointing to his scruffy beard. But the look also made him feel exposed on another level, particularly when he had to perform the dreaded orgasm face. “It’s the worst thing imaginable,” Dornan says. “For all the reasons anyone would think, most people would like to keep their sex face private. The idea of a million people seeing that! I hope it happens quite fast.”

Dornan is being accosted by people everywhere who warn him his life is about to change. “Everyone that I meet, people who run studios or other actors, everybody is saying, ‘Are you ready?’ I don’t have a good answer for that, because I don’t know what I’m meant to be ready for.” He’s had a few dinners with Robert Pattinson, who played what amounts to the PG-13 version of Christian in the “Twilight” franchise. “I’ve been around Rob enough,” Dornan says. “I’ve seen what it’s been like for him.” Have they chatted about the price of fame? “I don’t remember what we talked about the last time I saw him,” he says. “I think we just got drunk.”

Dornan recently learned first-hand about the dangers of drunk tweeting. He was at home with his family in Ireland over Christmas, and got properly smashed on vodka shots. “I woke up the next day, and I’d seen I’d tweeted the word ‘Christmas’ at around 1 in the morning,” he recalls. “I don’t know if I planned on saying more — like, ‘Christmas is a time of reflection.’ It made me wish I didn’t know my Twitter password and I wasn’t able to get on and do stuff like that.” That simple tweet still earned 10,000 favorites, and Dornan’s likely to collect many more groupies in the days ahead.

This spring, the actor begins shooting his next movie, “The 9th Life of Louis Drax,” a supernatural indie drama about a psychologist who treats a mysterious boy who has had a near-death experience.
“Do I want to be a movie star?” Dornan ponders when asked. “No, I want to have a career.” In the meantime, he’s focused now on being a dad. But he doesn’t think he’ll ever show his daughter the film that was born around the same time as her. “If she does see it, it will be way, way down the line,” Dornan says. “I certainly won’t be the one pressing start on the DVD player.”