Here's a proper introduction to angelkin, one of the playable races in Legends of the Dark Tower. I'll put up a set of caps to introduce demonkin on Friday.
If you're familiar with Dungeons & Dragons, angelkin and demonkin are basically like aasimar and tieflings; they're what you get when an angel or demon reproduces with a human. It's a fun idea to work with... but honestly, I mainly wrote these races into the LotDT lore because there's a bunch of cool cosplay out there that fits the concept, especially for demonkin. :)