It's not easy being Jake Gyllenhaal, what with everyone falling in love with you all over the place. Blue-eyed and muscular, with perfect brown hair, thick eyebrows, and consistently heavy stubble, the 24-year-old combines an unforced masculinity with a boyish openness and curiosity. He's not easy to pigeonhole, and he's also disarmingly down to earth, although he'd rather you not say that. "It bothers me when people say, 'Oh, you're so down to earth—for an actor,'" Gyllenhaal tells me over dinner at the Chateau Marmont in Los Angeles. "Even when they don't say 'for an actor,' I feel like that's the implication. Why are the standards so low for performers? I mean, I appreciate it, but it's still funny that people say that all the time."

People aren't likely to stop anytime soon. Gyllenhaal, that broodingly sexy scene-stealer of small, offbeat films, is about to go very big with starring roles in two of the most anticipated movies of the year. The first, Jarhead, directed by Sam Mendes and based on the best-selling Gulf War memoir by Anthony Swofford, features Gyllenhaal as a disaffected marine. At first glance, he seems like an odd choice for the role of "Swoff." In previous films (Donnie Darko, The Good Girl, Moonlight Mile, and October Sky), Gyllenhaal has played some variation of the sensitive, complicated, mischievous, misunderstood American youth. But Gyllenhaal says he desperately wanted the lead, and he reportedly beat out Tobey Maguire and Leonardo DiCaprio.

"My perception of Jake before I met him was that he was one of those drippy indie boys, doe-eyed and always feeling sorry for themselves," says Mendes. "But when I saw him onstage [in the London production of This Is Our Youth], he had a masculine presence I didn't expect. He does things in Jarhead where I had to step back and say, 'Wow, I didn't know you had that in you!' There are moments when he is really ugly, both physically and mentally."

That goes double for his performance in Brokeback Mountain, Ang Lee's beautiful and haunting adaptation of Annie Proulx's New Yorker story, which brilliantly depicts a complicated and painful affair between two young cowboys. Gyllenhaal plays Jack Twist, who is paired with strong, silent type Ennis Del Mar (Heath Ledger) to herd sheep in 1963 on Brokeback Mountain in Wyoming. After plenty of drinking on a cold night, Jack—the more easygoing and talkative of the two—invites Ennis into his tent, where he's soon cuddling up to him. Ennis freaks out, Jack doesn't take no for an answer, belts come frantically undone, clothes come frantically off, and one of them gets frantically fucked. It's a startling sex scene, and it's followed the next morning by predictable affirmations of heterosexuality ("You know I ain't queer"; "Me neither"). But soon enough they're back at it.

By the end of the summer Jack and Ennis are clearly in love, but they can't verbalize or acknowledge it. So they ignore it. The rest of the film follows them as they go on with their respective lives, never able to fully commit to each other but never able to completely let go of each other, either. "Brokeback Mountain takes all your conceptions of America, and the Western, and cowboys, and sexuality, and love, and it stirs them all up," Gyllenhaal says. "In the end, it's about how fucking hard it is to love somebody, to really be intimate, to really let go and be open to that, no matter what the context."