Hell, Griever dosnt even know what he is! Hence the song title: "Maybe im a Lion".............hes a confused individual.....heh

But seriously, it dosnt really matter what he is. Hes most probably a lion because of all the lion references. If you wanna ask that question about a GF then why not ask Pandemona what the hec he is. (My theory is that hes a random fusion of a Parrot (head hair), an Elephant (feet and legs), a fish (webbed hands), a Spider (butt) and a purple vacum cleaner (colour and face....creepy)