An imp feasting on the remains of it's unfortunate victim, alerted by bright sunlight coming from an opened door.
[Edit] Removed the bright highlights from the skull and toned them down on the pool of blood (thanks Jeremy & a3um). Kept the the glow but redone it with gray slightly darker colours (thanks Jeremy). And finally, I added the missing wing (thanks philippejugnet).
Ref: geirrodvandyke.deviantart.com/art/bare-ass-61205764 (thanks Jeremy).