Killer Mike and El-P are crushing, as Killer Mike and El-P are wont to do.

On a brisk, sunny Friday afternoon in San Francisco, the hip-hop duo known as Run The Jewels is on a giant stage in front of several thousand festival-goers at Golden Gate Park. Having entered to the triumphant strains of “We Are The Champions,” the veteran rappers are now setting about proving it. While trading rock-solid rhymes over concrete-shattering beats, they brush each other’s shoulders off. They deliver their bars with precision over DJ Trackstar’s drops and scratches — live vocals, none of the rapping along to a track that renders so many hip-hop shows messy facsimiles of fun.

This one feels like a fireworks display, and not just because El’s beats hearken back to the Bomb Squad. Mike, a gargantuan, rotund, 39-year-old black man from Atlanta, bobs his head authoritatively and at one point loses himself in a kicking dance that appears to be a Dirty South alternative to skanking. “I been smoking like a motherfucker,” he proclaims, which is true. El-P, a short, stout, 39-year-old redhead from Brooklyn, opts for enthusiastic leaping, intense outpourings at the mic stand, and a general look of confident elation. Eventually they welcome Bay Area turntablism legend QBert on stage to scratch. It’s an impressive display of skill, yet Mike and El’s own verbal acrobatics are every bit as awe-inspiring. Both on the brink of 40, they’re giddy unencumbered kids when you put them side by side with microphones in their hands. They appear to be having the time of their lives — but then, they usually look that way these days.

These guys would be the first to tell you that this world is a fucked up place. They were rapping about corruption and injustice long before they met each other, and they’re still rapping about it now. They’ve seen it. They’ve lived through it. Yet for Run The Jewels, life has been good lately. They are making the best music of their careers for a larger audience than ever. They are putting on concerts dynamic enough to exhilarate rugged rap traditionalists and the genre’s lunatic fringe alike, shows so good they even make believers out of curmudgeonly hip-hop skeptics. None other than Nas elected to release their feverishly anticipated second album, Run The Jewels 2, through his Mass Appeal imprint. And beyond the creative triumphs and booming business, they’re enjoying a late-blooming friendship that feels more like a blood relation. Here at the Outside Lands Festival, their bond is palpable long before they exit the stage together, Mike’s arm wrapped around El-P’s shoulder.

Offstage it’s all smiles too, mostly in the context of the most magnificent marijuana-fueled bullshit session you can imagine, which begins around a wooden coffee table in an outdoor VIP space flanked by food vendors and continues hours later in the dark, smoky confines of RTJ’s trailer. While sipping Grey Goose from a Solo cup, Mike mocks the festival-issued flasks for looking like birth control containers and comments that hotels in San Francisco “cost you a small elf-child.” Regarding the album title Run The Jewels 2, El remarks, “We stretched our imagination. We took mushrooms and meditated.” Mike says he’d like to bring El to Atlanta for three months and get everyone from Jeezy to Waka to Young Thug to jump on one of his beats. El replies that after such an experience he’d probably end up installing a stripper pole in his bedroom. There is also this exchange after I mention OutKast’s inaugural reunion show at Coachella, when the performance was cut short due to curfew just as Mike was taking the stage for a guest spot:

So, Mike, I was there at Coachella when you got cut off.

Mike: “Yeah, that was hurtful. That was fucked up, bro. For you to even bring that up is kinda like…”

El: “How dare you, man.”

Mike: “Maybe he doesn’t need to follow me the rest of the day.”

Oh, shit.

El: “Have you no heart, sir, at long last?”

Mike: “Can you imagine how that felt, bro?”

El: “Have you no decency?”

It must’ve felt really bad.

Mike: “So why did we bring that up? For real, what’s your real reason for hurting me right now, man?”

El: “Yeah, and you remember when you were a kid? And that kid stole your fuckin’ Big Wheel?”

Mike: “Yeah!”

El: “He stole your Big Wheel and he said, ‘Fuck you!’ And you knew you couldn’t do anything about it!”

The playful ribbing goes on for a while. Because they have just learned I am from Ohio, they ask me how it felt when LeBron James left for Miami. They inspire me to laugh nervously, then they mock me for laughing at Mike’s pain. And then, once they’re finished riffing, Mike gives a straight answer to my non-question about Coachella: “That moment — that moment fucked me up. ‘Cause I wasn’t sure I was coming back the next week at that time.” His reflections on flying across the country only to miss out on career pinnacle ring true. Moments later El-P is telling a dead-serious story about coming downstairs on Christmas morning as a kid and just knowing he was getting a computer, only to unwrap a shoeshine box and receive orders from his parents to hit the street and get to work. Run The Jewels being Run The Jewels, the punchlines have landed like punches and shit has gotten real.

***

Mike (real name: Michael Render) and El (real name: Jaime Meline) built respectable careers for themselves long before their paths crossed three years ago.

After coming of age selling crack in Atlanta’s Adamsville neighborhood — a time period he wrestles with dramatically on RTJ2 deep cut “Crown” — Mike did a short stint as a philosophy major at Morehouse College, where he met Big Boi and ended up rapping on some of OutKast’s biggest projects. Stankonia, “The Whole World,” Speakerboxxx/The Love Below: All of them won Grammys, and all of them featured Killer Mike. He released his debut album Monster in 2003 and spent the next eight years accumulating a strong, under-recognized discography on labels including Columbia, his own SMC-affiliated indie Grind Time, and T.I.’s Grand Hustle (then part of Atlantic). In a city increasingly ruled by freaky, spaced-out visionaries, he was fierce and authoritative — a hard-knock Southern stomper spouting political outrage with the fury of young Ice Cube and the swagger of UGK. Mike was an underground favorite in certain circles, and he was connected to just about everyone in Atlanta hip-hop, yet he largely went overlooked in the conversation about ATL’s greatest rappers. For a long time, it seemed like he would carry on as a perpetual underdog, always punching up.

El-P knows a few things about punching up. Long before Killer Mike’s rap career got off the ground, Jaime Meline was making a name for himself in New York, establishing an underground legacy that veered from jazzy boom-bap to skewed, volatile hip-hop futurism. After moving to Brooklyn as a kid, at age 18 he dubbed himself El Producto and teamed with Mr. Len to form Company Flow; they later added Bigg Jus to complete the trio. The group signed with Rawkus, the most popular and influential underground hip-hop label of the late ’90s, and released the acclaimed Funcrusher Plus. By ’99, El started his own label, Definitive Jux, which took over for Rawkus as the leading underground darling of the early 2000s largely on the strength of his bruising experimental production style and a keen ear for outside-the-box talent. During the same era he was part of the Weathermen, a rap collective featuring many of his Def Jux associates (Aesop Rock, Vast Aire, Cage, etc.) plus eccentric visionary Camu Tao and other members of Columbus, Ohio’s MHz crew. On top of all that, El-P is perhaps best known for his solo albums, which tend to be tense, paranoid, hard-hitting cultural treatises — not unlike what’d you hear on a Killer Mike record. Although El-P’s solo releases only come around every five years, they’ve always been event records among those in the know. Even in 2007, with Def Jux’s cultural clout on the wane, I’ll Sleep When You’re Dead was received with hosannas, if only by the small cadre of listeners who knew who the hell El-P was. As he raps on “Jeopardy,” the first track on Run The Jewels 2, “I’ve never been much of shit, by most measurements don’t exist/ A radar little blip in the shadow of motherships.”

Despite a vast number of similar ideas, influences, and aesthetic preferences, for years there was virtually no overlap between Killer Mike’s world and El-P’s world. Mike was a gangster rapper from a background not unlike the TV show The Wire; El was a backpack rapper who was covered by the British experimental music magazine The Wire. But as mainstream rap declined from dominance, separate spheres began to merge and morph. Kanye West and his many disciples dissolved the perceived distinctions between conscious and commercial rap. The internet flattened the playing field. What would have seemed unthinkable around the time Killer Mike and El-P released their debut albums had become realistic and even reasonable by 2011, when Mike sat down with Adult Swim’s Jason DeMarco to discuss making an album together.

As Adult Swim’s creative director for on-air — essentially he’s in charge of everything but the shows themselves — DeMarco cultivated a hip musical tradition within Cartoon Network’s grown-up programming block, complementing the schizoid surrealist visuals with sonic equivalents like Flying Lotus. That tradition extended beyond TV with the advent of Williams Street Records, the Adult Swim-affiliated record label DeMarco co-founded in 2006. Williams Street teamed with Def Jux in 2007 for the Definitive Swim compilation, and that same year Adult Swim’s team made the animated video for El-P’s Trent Reznor collaboration “Flyentology.” DeMarco continued to work closely with El over the years, so when Killer Mike said he wanted to collaborate with Williams Street on an album he couldn’t do anywhere else, DeMarco had an epiphany.

“I immediately thought, ‘You should do something like the music that inspired you when you were a kid because you’re one of the only rappers who can do political rap in a real way. It’s part of who you are. And nobody’s doing that right now,'” DeMarco later tells me. “And he said yeah, ’cause one of his favorite records is AmeriKKKa’s Most Wanted. And my favorite hip-hop record is Death Certificate, period. I said, ‘Look, if we want to do that, I know the perfect guy.’ …And then when they met, it just became the love story.”