Well for the first sight you can tell "It's not very original", battle between angel and demon, it's almost like 1283784657885947 time you see it. But for me it was the greatest challenge. Drawing armour and creating demon took a lot of effort, time and discipline. Especially when almost all the job was made by mouse, not tablet. If I would be original I'd create something like old nasty-looking black tree with beautiful flower, but I wanted to do something which would stuck me into thing I must work on I must develop and make slowly step by step. I took challenge instead of original idea.
Another thing is, I really like hybrid image of demon, at the beginning I had no idea how to create interesting look for demon. He had to be opposite of ideal creature which is angel- embodiment of all we think is connected with God- the ideal being. So we have conflict of Angel/Demon, Ideal/Chaotic being, Light/Darkness, they're fighting. And as the circle symbol I put here means that this fight don't have beginning nor end, it's just never-ending epic battle which we all know but not always keep in our minds.
This moon has been infected... ...in fact - it is infected for millenia. These creatures need a lot of time to evolve - they are pretty harmless (except the fact they make their nests from moons and planets that have molten core). Their eggs orbit around the nest (moon/planet) for really long time until they hatch. They probably don't need air or any other known elements to survive. All we know is that they prefer planets/moons closer to stars and need a lot of heat/energy to give birth to the young ones.
//Inspired by Farscape series. Living Leviathan ships gave me this idea.
Edit: Added some details here and there, changed colors here and there. Nothing dramatic.