What is a Halfwing?
A derogatory term for someone whose parentage includes an ariel and a human. Halfwings look like humans with stunted (half) wings. Because their wings aren't fully formed, they can’t fly.
What is an Ariel?
Ariels are a race of humans with wings. They are basically angels but are neither magical nor divine.
What's the social structure of all these races (halfwings, humans, and ariels)?
Socially, Ariels look down on non-flying humans who in turn look further down on the abominations known as halfwings (ariel parent and human parent).
What is Blu?
Blu is a somewhat rare luminscent mineral that many nations struggle to control. It’s an extremely profitable drug but has other spiritual and magical uses (cloaking/invisibility, gliding, etc.). Several fringe religions are based on the mineral and rumored to unlock its true potential.