I'd like to see this too, but I'll give you what I can!
Studying a character you want to play really thoroughly is a good idea in general(I personally take notes on every single trait I notice and what every action they take--even the most mundane things--could possibly mean about them when I canon review), but it's especially important when you want to play and build on a minor character. You don't have as much to work with, so make sure to use it to its fullest. This is especially helpful if you don't want to/can't go too far into headcanon for an app.
+1
Studying a character you want to play really thoroughly is a good idea in general(I personally take notes on every single trait I notice and what every action they take--even the most mundane things--could possibly mean about them when I canon review), but it's especially important when you want to play and build on a minor character. You don't have as much to work with, so make sure to use it to its fullest. This is especially helpful if you don't want to/can't go too far into headcanon for an app.