Detroit’s Royce da 5’9″ remains one of the most criminally underrated emcees in modern hip-hop, and it’s partly due to his style. He’s known for adopting drastically different vocal timbres and cadences verse to verse—even bar to bar—and therefore rarely sounds the same on the mic. Even for longtime fans, it can be difficult to identify Royce’s raps by ear and give credit where it’s due.

The general lack of credit is also thanks to his long-running association with Eminem. They’ve been sparring partners dating back to Eminem’s first album, 1999’s Slim Shady LP, when millions of American kids were introduced to Royce via the song “Bad Meets Evil.” The song is a back-and-forth game of lyrical one-upmanship between two cartoonishly offensive characters doing each other’s sound effects. They trade rapping the hook, “‘Cause this is what happens when Bad meets Evil/And we hit the trees ’til we look like Vietnamese people/ He’s Evil, and I’m Bad like Steve Seagal/Against peaceful, see you in hell for the sequel.”

They both went even harder as Bad Meets Evil, issuing a full-length album in 2011, Hell: The Sequel. Royce’s flows outmatched Eminem’s throughout (though few will admit it). He’s always operated in the shadow of Slim Shady despite his dizzying technical abilities and history of producing solo music of substantial artistic merit.

His acclaimed seventh studio album, The Book of Ryan, which he released in May, is moving, soulful, and autobiographical. But most casual rap fans know it only for the fourth single, “Caterpillar,” a track on which Royce and Eminem trade verses with the over-the-top braggadocio of their early work. “My pen is like Big Ben, this shit’s just a classic waiting,” Royce raps. “Your favorite rapper come at me, I just decapitate him.” Maybe we should just face it: Eminem and Royce da 5’9″ bring out the best in each other, but it’s time for Royce to take a turn in the spotlight.