Beauty Editor Elaine Welteroth Hung out with Rihanna in Barbados—Come See What Happened

When I enter Rihanna's hotel suite overlooking Sandy Lane Beach, her sprawling crew (including her mother, aunt, manager, and three personal photographers) is busy at work. Meanwhile, the Lanvin-clad superstar is tucked into a corner, mid–duck face. She's posing with her new M.A.C. Viva Glam lipstick while her bestie–cum–staff photographer, Melissa Forde, snaps pics. Images of the new shade have just mysteriously leaked into the blogosphere, sending her handlers into a dizzying panic. But not RiRi; she's as cool as a cucumber, even in 100 percent humidity.

As the new face of M.A.C. Viva Glam, the singer is following in the footsteps of Lady Gaga and Nicki Minaj in an effort to support the M.A.C. AIDS Fund, which has raised a remarkable $300 million in the fight against HIV and AIDS. The cause, RiRi tells me as we cozy up on the couch, is close to her heart: "I've been around so many people who have been affected by HIV and AIDS. It's my turn to spread awareness. Because when people don't talk about this, they feel like it's not happening." And that couldn't be further from the truth.

According to UNAIDS—a United Nations partnership that focuses on universal access to HIV prevention, treatment, care, and support—approximately 2,300 young people become infected with HIV each day. Even scarier: Globally, HIV infection rates are twice as high in young women ages 15 to 24 as they are in young men. "Nobody is safe unless you protect yourself," the star says ardently, fixing her piercing green eyes on me.

Many will argue that Rihanna is an unlikely role model to spread the gospel of safe sex, what with her racy Instagram feed and explicit music videos (I mean, have you seen "Pour It Up"?). But with a whopping 125,887,954 followers at press time (me included!), the undisputed fact is: Girl's got our attention. And according to @badgalriri, she wants to use it for good. "My contribution is that every penny from the cost of this lipstick and Lipglass goes to help someone who really needs it," she says. "I am doing this especially for young girls."

Reflecting on her own teen years, the reformed tomboy admits she was a late bloomer in the dating game due to one unwavering barrier: a strict mom. (She says her flat chest and mosquito-bitten skin didn't help, either: "It was a horrible combination!") "I wasn't allowed to date. At 13 my mom would tell me, 'You can have a boyfriend when you're 16.' And then at 16 she'd say, 'I never said that—and as a matter of fact, it's 40!'" (When she tells me this, I hear her mother giggle from across the room.) As RiRi opens up about everything from her hard-to-imagine awkward phase to her mission to save lives one lipstick at a time, the most beautiful girl in the world gets, well, even more beautiful.