I came up with this AU whilst chatting to my brain twin muddlethrough a couple of months ago but shoved it on the backburner because a) I wasn't sure if there was appetite for wingfic!AU in the Berena fandom and b) because real life was kicking my butt.
Anyhow, the basic premise of this AU is that only consultant-level doctors have wings. I believe that the backstory/history that we came up with was that all humans have wings as a dormant gene, or something along those lines, to be triggered chemically when certain professional milestones in life are met. I think we went so far as to explore a side-plot where the hospitals see botched triggers of wing-growth by black-market chemicals, but that's a story for another day. We might also have talked about other distinguishing features of other professions (we mused about how barristers, for example, might have uniformly black wings, or wings of a different structure and/or texture - i.e. bat's wings), but again: story for another day.
I'm not sure how developed this AU is, or indeed how much I'm going to play in this world, but I figured I should probably post what I have, just to get my writing muscles limbered up again now that I have a couple of days free.
So, here it is, I suppose.
My everlasting thanks, as ever, to my braintwin muddlethrough (lindsey_grissom) for talking this through with me.
Come look for me on tumblr (same username as on here) if you want to chat about this AU!