User blog comment:JustSomeDude.../Moriah is the Weirdest Looking Dude/@comment-5690257-20150530213607

I personally think (although this may be speculation) that the Kage Kage no mi as a side effect forces you to look like a demon (and by this Moriah ate it at a young age). It would make sense and would be a cool drawback for such an op devil fruit