As a child, Stephen Bruner had two favorite toys: a plastic ThunderCats sword and a bass guitar. That's how intertwined the 27-year-old musician, who records spaced-out R&B under the name Thundercat, is with his instrument. And so, when one asks why he gravitated toward the low end, despite having a father and an older brother who played drums, it's sort of like asking what made him play with finger paints or eat mud or do whatever else kids do when they're too young to know why they do anything. 

"My mom likes to say I just had a natural affinity for strings," says Bruner with an almost audible shrug over the phone from Los Angeles. "Every picture I look at from when I was a kid, I have a bass or a guitar in my hands."

For Bruner, music is just something he's always done. As such, he's nonchalant about his skills. He's a virtuoso, to be sure, but one who places melody and atmosphere above braining the listener with a torrent of notes. The two albums he's released as Thundercat are so loose, almost weightless, that their complexity isn't always obvious. His approach to songwriting is an extension of his personality. Although a committed jazzhead, who'll casually name-drop Jaco Pastorius and Stanley Clarke and studio musicians only other musicians are familiar with, Bruner is just as apt to discuss his music in the context of the X-Men or Adult Swim or Sonic the Hedgehog. He's no Guitar Center wank anxious to show off his sick fretwork. He doesn't have to.    

"Not everyone wants to know everything you can do," he says.

Anyone who is interested in sampling the breadth of Bruner's ability, though, is free to check his wildly varied résumé. He's played in everything from wedding bands to hardcore jazz ensembles to Snoop Dogg's and Erykah Badu's touring bands. At 15, he was in a glorified boy band that had a hit single in Germany. A year or two later, he joined his brother in the long-running California thrash outfit Suicidal Tendencies. "It gave me a lot of confidence as a bass player because of the things I had to do," he says of playing for punk audiences. "I'd start the songs and people would be looking to me, and if I sucked, I'd get a boot right to the head.” 

But his solo career didn't take shape until he met electronic music producer Steven Ellison, aka Flying Lotus. The two connected a few years ago, and it was "like Jay and Silent Bob meeting for the first time," as Bruner told Pitchfork. Bruner played on Ellison's groundbreaking Cosmogramma album, while Ellison co-produced the first Thundercat record, 2011's The Golden Age of Apocalypse, lending his cinematic eye to a record blending '70s jazz fusion, stargazing soul and ambient electronica into a head-tripping cosmic swirl.   

"We don't always see eye to eye on everything," Bruner says of his relationship with Ellison. "A lot of the time, he'll think I'm retarded and I'll think he's crazy or whatever. But deep inside, there's a symbiosis we both work with, and I think it translates to the music."

Apocalypse, Bruner's latest album, also co-produced by Ellison, exists on the same celestial plane as its similarly titled predecessor but is grounded in more earthly concerns. The boogie-funk jam "Oh Sheit It's X," for example, finds Bruner singing, in an airy falsetto, about dancing so hard at a party he forgets to eat. It's not always that frivolous: As the title implies, the album is rooted in catastrophes, both big and small, from the economic collapse to the death of Bruner's close friend, the composer Austin Peralta, who's the subject of the heavenly, string-abetted suite that concludes the album.

But then there's something like "Tron Song," featuring a skittering, Flying Lotus-style beat and Bruner crooning, quite lovingly, about his cat. Though he's gone through some tragedies in the past year, it clearly hasn't changed the nature of who Bruner is: an artist for whom playing music and playing around are basically the same thing. 

“I play Grand Theft Auto all day,” he says. “And when I’m not playing Grand Theft Auto, I’m playing the bass.” 

SEE IT: Thundercat plays Bunk Bar, 1028 SE Water Ave., with Grammies, on Thursday, Nov. 14. 9 pm. $15. 21+.