Got sidetracked but about the notes: I'd remembered having this idea when I listened to Avi Tran and Sura from the Crewniverse talk about the instruments/sounds associated with characters in the shows cast. I'd say that was the first thing to inspire me with such a thing but actually goes back to "Peter and the Wolf" where each of the characters in the musical (?) were represented by an instrument. I loved seeing it on PBS because it just seemed so clever and not only did the characters personality shine but that of the instrument.
So getting back on track to my own characters I've only really thought of it in abstract and ironically while brainstorming for this thread I'd thrown together a random little song thing related to characters of one of my WIP stories. That being said I think these instruments correspond to some of my most frequently explored characters.
Kiren - Electric or Acoustic guitar. Both though more the former can be really powerful and leads well as does Kiren but can also be pretty wild and I think it suits his calm but sometimes fierce personality.
Socket - Synth piano. It's got a fun playful kind of sound to it but if played right can also produce more mellow sounds which is 100% on key with how she is.
Rye and Haku - both are in the chiptune/8-bit digital instrument category and whats great about it is the variety of tone. Haku's tending towards more bright and playful tones versus Rye's being a bit more wild and in some cases kinda crazy or strange (think Earhtbound)
Aileen - Something like a kalimba or 8-bit. It's got a very cute sound and just makes me thing of the curiosity of youth and the feeling of looking at things with new eyes which is a big part of their personality. Which isn't to say they don't have their sassy or spunky moments so the funky side of 8-bit would fit her well.
Lucid - definitely Piano. Loud and powerful when it needs to be but also soft and delicate and she's very much both, being a commanding but also very caring.
Nona - DRUMS! The can be quiet they can be loud and Nona 100% goes to the beat of their own. They're actually kind of a vent oc so the point was to let them be loud in places where I was quiet, so it fits
Max - Modular synth. Not sure if it counts as an instrument but anytime I think about him it's eurorack and synthwave stuff coming out of one of those bad boys. He's got a very cool demeanor but can be a force to be reckoned with if you push the wrong buttons.
Vi and Mono are just variants of myself so picking an instrument its tough but in terms of sound it's honestly pretty broad. If anything it'd probably be a mix of all of the above given my characters all have little fragments of myself mixed in so to pick just one wouldn't work ^^;;
Honestly though I've got a lot more than just these but they're the main folks from my current comics Foxtales and Gekkering so I figured I'd stick to those