However I'm not sure how to go about it, aside from solo flashbacks. And I want interaction at Xy, which can't really happen w/flashbacks.
I want to get him to the point where he is more accustomed to sunlight and more skilled at bonecrafting, very skilled at violin. Ultimately, I want him to be playing violin to worship and communicate with Leth. I remember vaguely thinking that maybe, he could get a Gnosis mark but I don't remember which one I was aiming for him to earn.

Three years is sort of long though. Assuming he did all this, he'd probably have a specific goal in mind and working hard towards it wherever he is. So I'll be busy writing flashbacks.
Cost of living, I have to add that up right? Anything drastically change since 511 AV?