#but if eventually a human sings a solo with invisible accompaniment and nothing the instrumental could be coming from. ill eat my hat

[lapislazulillie]

Useless Steven Universe Theory:

Gems have the power to project music out of thin air.

I’m sure this has been observed by others before, but there’s no outright confirmation in the show so...basically, all of the singing and music in Steven Universe happens in-universe rather than as a representation of emotions/thoughts like in most musicals. When humans sing the accompaniment is always shown as happening within the show--Steven’s ukulele, Greg’s guitar, Sadie and the band’s instruments, etc. 

Gems, however, bring in non-diegetic accompaniment when they sing--instruments the audience hears but doesn’t see. The singing is still singing to the characters, though, as noted by characters like Peridot and Spinel.

This rule is only possibly broken in Mr. Greg with the titular song and the Empire City song, but then again, Steven is there for the whole time and could be providing those accompaniments. On another hand, Mr. Greg is specifically meant to be a Musical episode, so it might be following the rules of traditional musicals rather than the rules of the rest of the show.

This is a Gem power that Steven develops over time too, like in Full Disclosure when the accompaniment for the song comes from both his phone and an unseen band of guitars & percussion. Before that episode, Steven almost always has physical instruments--except for the Cookie Cat rap in Gem Glow, which...it’s likely that accompaniment was just taking place in Steven’s head. In Coach Steven, it even makes a point of showing Steven turning up his boombox to hear the cool guitar instrumental for his part of “Strong in the Real Way.” 

It’s also worth noting that the crew often talks about how each Gem is assigned an instrument (Pearl’s piano, Garnet’s synth bass, Amethyst’s electric drums, Spinel’s reverse violins, etc), and that instrument is usually primary when a Gem sings. Other instruments come in as well, but they’re secondary. Playing your unique personal instrument is like summoning your unique personal weapon!

This isn’t to say all of the music in Steven Universe happens in-universe--I think most of the background score without lyrics is just for the audience, and things like the non-guitar sounds at the end of “I Could Never Be Ready.” Fusion dance music is probably projected in-universe by the Gems, with the possible exception of Malachite’s birth. Then again, maybe Lapis is just That Bitch. She went for the dramatic dip there, maybe she went for dramatic music too.

So yeah. All the times in your life where you wished you could have a personalized soundtrack you could hear? Gems can and do. I don’t expect any future seasons to openly acknowledge or confirm this (because, like i said at the top, its completely useless and just a fun little detail), but I am confident that the patterns supporting it will hold up!