well since I do not draw for some years, that will be a nice try
From mythology Cerberus means "the devil from pit" or it is know as "hound of Hades"; He was a monstrous dog multiple heads that guarded the entrance to Hades (literally what we mean as hell), the underground kingdom of the dead, leaving the souls enter but never leave, shattering the mortals there ventured.
Then taking into account the real meaning of "hell hound" nothing better than a cerberus; But the most important part of my inspiration was my own Rottweiler using its beautiful original appearance, and making it into a hellish creature slowly. After all a furious Rottweiler by itself is an impressive figure.
I decided then split into parts, 1 original appearance; 2-did the design of the final look, something that I could see it would be possible to erase a little and split into two, thus the stage 2, is a fierce creature, twice bigger than a normal dog; 3- a hideous creature, bigger than a tiger and two hideous heads, with fulminating eyes, their saliva is lava; with natural thorns on the eyes and neck, his legs when it stepped on the ground are able to make any vegetation to ashes.