Diablo

this is Diablo's original form.

Diablo: sensory demon

-body is essentially made up of eyes (with teeth) but they are usually closed giving the appearance of smooth flesh.
-Has large bones erupting from it's back: can be used to lift Diablo off the ground and he can move around using them while also using them as weapons to crush and stab opponents.
-Large sharp metal claws while his teeth are made of bone.
-His signature ability is to absorb iron out of anything- including blood. The absorbed iron can be manipluated and used to create protective armour or form the membrane between the large bones and allow him to fly.
-He is very agile and fast.
-Prefers to go for the quick kill.
-Long strong tail acts like a whip and also provides balance.

uh..... i don't know what else to say..... OH!

Diablo was the first demon to become a human's soul. He has been around for several millenia and has obtained a vast amount of knowledge. He prefers to possess those of the same bloodline. Like most other demon souls, while possessing his first few humans he did not know how to restirct the power available to them, or even know that he should, and they transformed into his flesh form. Demon bodies are not adapted to survive in the human world but they can last for 1-3 years before they finally decompose. In this form neither the human nor the demon is fully in control and the body is mainly running on basic instinct.
Some of his hosts demanded his power and simply took what they wanted and they used his power to do as they pleased. Evenutally they would also transform into Diablo's flesh form after using too much of his power.
Diablo was one, if not the most powerful demon on earth during it's early years and because of this he accumulated a reputation and was referred to as the Devil- Or Diablo, as he prefers to be called. ^^

Well, there ya go! A little background info on the infamous demon. ^^