When Brittany Hazzard was 11, she noticed that Lil Bow Wow, then just a couple of years her senior, seemed to be everywhere. Though she had never tried rhyming before, she figured that she too could become a kid rapper. “I was writing down 3LW lyrics in a notebook,” she recalls. “I don’t know why I was writing them down like they were mine, [but] this kid was like, ‘You wrote these?’ and I was like, ‘Yeah.’ ” The encounter convinced her that she needed to create her own material, so the next day, she came to school with a song she had written herself.

She hasn’t stopped since. In the last few years, Hazzard -- who now writes and records as Starrah -- has written for superstars like Travis Scott, The Weeknd, Drake, Halsey, Katy Perry, Nicki Minaj, Camila Cabello, Maroon 5 and Rihanna. The latter’s woozy 2016 smash “Needed Me” bears the hallmarks of Starrah’s rich melodic style: It’s part revenge anthem, part brag fest, but Rihanna seems to sing between sighs, letting ideas dissipate but never entirely disappear. The attitude comes across as 100% Rihanna -- even though, says Starrah, the song pulled directly from her own romantic history. “The way it translated to other people was a good feeling for me. It changed my perspective on my ability to write a universal song,” she says. “I dated a girl who told me that I helped her get out of her old relationship with that song.” She pauses. “That’s crazy.”

Starrah’s eye for a song’s tiny, evocative details, as well as her insistence on keeping a low profile, have made her a true top 40 chameleon, one who can write for pretty much anyone without letting her style overtake theirs. She avoids being photographed when possible; when she is, she often obscures her face. Her social media presence is fairly minimal, though she admits to creeping on artists’ profiles before sessions to gain insight into their worlds. In person, however -- today, we’re sitting in an artist incubator house her manager runs in the hills of Los Angeles -- Starrah is warm and attentive, almost probing, as if she’s analyzing my speech patterns to better understand who I am.

After graduating from Delaware State University, where she would reach out to writers and producers on Myspace, Starrah moved to Los Angeles and worked day jobs at Urban Outfitters and Puma, crashing on a friend’s couch to save money as she pumped out songs. In 2014, she released the confessional “Low,” a rework of Drake’s “Heat of the Moment” that introduced what would become her signature: vocals that aren’t exactly sung, but not quite rapped, either. Halfway through the track, she breaks into a shockingly candid verse: “PTSD from my childhood/I woke up for cereal one morning/SWAT team kicking down the fucking doors/Older sister handcuffed on the floor.”

It’s a powerful image, but Starrah can also vividly render mundane situations. While in the studio with DJ Mustard in 2015, she noticed he carried a pair of cellphones -- an observation that formed the basis for rapper Kevin Gates’ “2 Phones,” which went multiplatinum. It’s a song about juggling everything from women to drug deals, but the chorus -- in which Gates’ voice hiccups every time he says the word “two,” stretching the pause before “phones” -- conveys the painful weight of responsibility and power. “I can’t write melody unless I have lyrics,” says Starrah. “I don’t know what emotion I have if I don’t have words” to describe it.

Recently Starrah -- who’s published by Pulse Music/People Over Planes -- started working closely with Madonna, who came to her with multiple song ideas that turned into half a dozen tracks on her new album, Madame X. The pair sorted through the fragments, singing different melodies until they hit on the ones that felt right. For a writer who had spent years toiling behind the scenes, it was the ultimate “I made it” moment. But Starrah says that even in the presence of the queen of pop, her fly-on-the-wall approach is the same. “I just listen to who [artists] are as people,” she says. “The most I can do is get inside their minds and see what they’re thinking.”

This article originally appeared in the June 15 issue of Billboard.