Cool! I especially like the eyes. Oh, and unrelated to the image, but it turns out the mouth on the original Jeff image was taken from the corpse of a wolf. This seems to support my theory that Jeff isn't entirely human... creepypasta.wikia.com/wiki/Use…
did you know that Jeff is not entirely real? the reason why they used such an image for Jeff's mouth to accentuate Jeff's slit mouth.... to say that he is not human is like saying that he did not have human parents and that he did not have a human brother and that he never sliced his smile into his face and burned away his eyelids.... what you are suggesting is that he was born inhuman.... and that is not how the rest of the fandom sees Jeff, Jeff is a human, though he claims to be a demon (but then again most killers refer to themselves as such) he is no such thing. He is a living breathing red blooded male human who has the mental illness that causes him to kill as much as he does.... a simple photo editing does not put into facts of that is what the character is.... Your theory is alright and it is neither right nor is it wrong, but with what evidence you provided it does not seem as likely as you may think.
Well, him being a mutant would help explain his abilities, like inhuman durability and super strength. But like I said, it's just a weird-ass idea I have. According to my silly theory, the "burning sensation" wasn't insanity, it was his previously-dormant powers activating.
hmmm.... Well the theory is a good one for an Xmen OC not really CreepyPasta character, he does not possess inhuman strength, he is just really hard to kill. And as someone who has experienced that same burning sensation does not make me a mutant myself.. what that sensation Jeff felt was is hatred.... he was being told what to do, he was deprived a best friend (aka brother) and he was insulted to boot.. he snapped and it was because of insanity that he snapped... the theory you have would go great with a character of your own creation but not so much Jeff