Thinking about Theo and music....
So originally I thought "Theo can't sing." But I also got a fair bit of inspiration for his relationship to Cheliax from Captain Von Trapp's relationship to Austria from the Sound of Music (deepest apologies to Messrs Crowley and Fell), and I just had an idea...
So when he's young, Theo isn't necessarily great at singing, but it's one of the ways he keeps his spirits up on his 'low' days - unlike most gnomes, he started bleaching in utero, and I have it manifest for him largely as childhood depression, kept in check partly by his anxieties. Theo's mom taught him to sing when he's down or scared (assuming it's safe to do so), even if it's just a silly song about how much he hates everything, because it will help keep him from complete despair. So he sings a lot in his youth, but never as a performance. It's always for himself.
When Thrune takes over, I imagine there's something of a crackdown on what is and is not acceptable music. Songs and ballads are a way of retelling history, after all, and Thrune has always been very careful about controlling the people's understanding of history. So most of Theo's favorite songs - especially the ones about what it means to be Chelaxian - probably became straight up dangerous to sing. And since a lot of what Theo is upset about during this time isn't safe to admit aloud, he can't sing his silly little "I hate this" songs. There are some songs that are still safe - Cheliax didn't crack down as hard on Brastlewark because they didn't want to deal with the GNOMES, so silly Brastlewark specific songs are probably fine, but part of why Theo loved the Chelaxian songs is they gave him a sense of identity (something he struggled with as a young man) in a way the more whimsical gnomish songs didn't. He tries to keep singing to himself to keep his spirits up, but censoring himself just reinforces his grief, so he eventually stops singing altogether. It's part of why he declines so quickly - he is essentially grieving in secret, totally isolated, and without his usual coping mechanisms.
Once the bleaching runs his course, of course, Theo is a very different person. His emotions have muted enough that singing to himself for comfort is largely unnecessary. He kind of forgets he used to sing to himself for years - to the point it doesn't even come to mind while raising Qweck. Its partly a defense mechanism - it just isn't safe for him to remember that aspect of himself. It's not until he flees to Kintargo that he remembers.
Kintargo's prominence in the Chelish Opera scene and the unique Kintargan dance halls suggest to me that the city's culture is very musical. So I imagine that not too terribly long after fleeing Brastlewark - after Giliys's patron has been dealt with but before he knows what he's going to do with himself now that being a librarian seems out of the question - Theo is wandering the city, and he happens to pass by a school and he hears singing. It sounds like some kind of chorale practice, which is common enough - even in Brastlewark, they had a children's chorus (though it sounded dreadful because they could never get the kids to sing the same song at the same time) - but there's something bout this chorus that stops him in his tracks.
They're singing the old songs.
Songs about Cheliax and her history that Theo hasn't heard since before the Ascendancy. Songs he forgot he knew because it wasn't safe to know them. Songs that carried him through some of the most difficult days of his childhood, that he had to forget during the most difficult days of his adulthood.
That's when Theo knows he's going to be alright. Because whatever else is going on, there are children who sing the old songs. He's never going to sing as much as he did in his youth (even if he was so inclined, spontaneously breaking out in song in the middle of the street is less accepted in Kintargo than it was in Brastlewark), but after that, from time to time, he'll catch himself humming to himself - and then he'll allow himself to continue because he's safe here.
And during those times when he's overwhelmed and afraid and alone - especially during that year when Giliys and Qweck run off to hell to try to retrieve the souls Giliys damned for his patron - he'll go for a long walk around the city, and somehow his feet will always take him outside that school, to hear the children sing the old songs.
