Caim appears in Ars Goetia, the first part of Lesser Key of Solomon as a Great President of Hell, ruling over thirty legions of demons. Much detail is offered: he is a good disputer, gives men the understanding of the voices of birds, bullocks, dogs, and other creatures, and of the noise of the waters too, and gives true answers concerning things to come.
He is depicted in 19th and 20th century occultist illustrations as appearing in the form of the black bird called a thrush, but soon he changes his shape into a man that has a sharp sword in his hand. When answering questions he seems to stand on burning ashes or coals.
Caim's name seems to be taken from the biblical first murderer, Cain.
I'm going to try to do pretty much everything in zbrush for this guy, in my spare time after work. Probably won't be posting many sketches since I'll do my concepting in the program.
I have quite a few symbolisms I want to incorporate, but I'll see how many I can do and keep it nice and tasteful (and also not take too long to make).