The year 2013 may be forever remembered as the year “indie” became roughly as mainstream as “alternative” became 20 years prior. As a result, the music-listening public has acquired increasingly left-field tastes, crushing on bearded banjo lumberjacks and rocketing a sixteen-year-old New Zealander up the charts with a single that’s literally just vocals, bass and finger snaps.
Yet less acknowledged is the influence the underground had on hip-hop in 2013. Many of the major hip-hop releases of 2013 were inspired less by the Maybach Music/Roc Nation radio-rap sound that was in danger of becoming “traditional” in favor of dark and oppressive sounds from the underground. As the trend of druggy, ambient “swag-rap” faded away, both underground and mainstream rap grew gnarlier, artier and a hell of a lot harder to listen to.
One of the main catalysts for this sea change was good kid, M.A.A.D. city, the major-label debut by former underground star Kendrick Lamar and arguably the 2010s’ first true modern classic. Having ended up near, or at the top of, nearly every critic’s year-end list (including mine — I ranked it as #2), it’s already had a tremendous influence on rap. Chance the Rapper’s Acid Rap, which will probably end up as the most influential rap album of 2013, was not even ashamed of the cues it took from Kendrick. And good kid’s single “Backseat Freestyle” ushered in a new era of rap singles driven almost entirely by lyrical virtuosity — Eminem’s “Rap God” and Drake’s “Tuscan Leather” could not exist without it.
Yet the most interesting thing about good kid is how it managed to get so popular despite being one of the bleakest major-label rap albums I’ve ever heard. Even Biggie’s Ready to Die, an incredibly sad album, has the capability to fade into the background at parties.  Not good kid. Though it has two or three major bangers, most of the album is difficult, turbulent and brooding. It’s a work of art with mainstream appeal, but in no way is it a party album.
The other main artist to influence hip-hop’s sonic landscape in 2013 came from even further underground — industrial hip-hop group Death Grips, who released the twin albums The Money Store and No Love Deep Web in 2012. Death Grips is more of an indie rock band than a rap group — their live setup is more in line with rock, and their drummer previously played with noise rock acts Hella and Marnie Stern. Yet they’re hugely popular, and they’ve given the hip-hop community a new taste for minimal, abrasive production. Kanye’s Yeezus could not exist without Death Grips, nor could Pusha T’s mostly Kanye-produced My Name Is My Name.
Yet perhaps the most visible manifestation of the rap public’s new love of being confronted is the hype surrounding Chicago drill rap. Hipsters have had a controversial interest in this still-insular scene since leader Chief Keef blew up in 2012, leading a lot of music fans to wonder “why?” Keef isn’t a technically gifted rapper by any means, and his beats were all done much better three years ago on Waka Flocka Flame’s insanely influential Flockaveli. 
I believe the answer lies in rap fans’ interest in being challenged — nay, terrified. Chicago drill is almost always discussed in relation to the city’s alarming murder rate, and rappers like Lupe Fiasco and Rhymefest have accused drill of glorifying the violence that has led Kanye to label the town “Chiraq.” Though the ethics behind hipsters enjoying drill music for this reason are extremely questionable, drill is still representative to many listeners of a legitimate “street” perspective — another reason the largely gang-themed good kid, m.A.A.d city may have appealed to listeners.
Whether it’s because of the underground noise from Death Grips and Kendrick Lamar or a disillusionment with the often friendly and chilled-out “swag rap,” hip-hop is becoming increasingly confrontational, and weird. While hip-hop in 2011 was mostly for partying, chilling out, and/or getting pumped up, 2013’s rap is more introverted. It’s music you listen to through headphones rather than speakers, challenging music you feel in the gut rather than let drift through your head. For the first time in a while, rap truly feels like something cutting-edge and dangerous, something your parents or even your older sibling will never, ever hope to understand.