It's a quick and fun read! I enjoyed the wee bit of body horror that foundling "puberty" provides >:3c Worldbuilding is neat, too. The "angels" and "devils" have it two different kinds of bad, where one is locked in a cage and one is ignored except to get yelled at, so even if the cage seems nicer you can see why Asher is 1000% against that idea.
Also: The detail of the feathers / wing art throughout becoming black towards the end is a nice touch.