That's funny, I never thought of Fred or George as any sort of ape or niffler. I always saw them as something a little less *runs after word, which just escaped brain* flashy(?). Maybe something like big cats, or wild dogs. Whatever they are, I'd have Fred as something big and showy, where as George would be quieter, more compact, and, ironicly, more likely to survive. Ummmmm....... I think I'd have them a lion(fred) and a puma(George). Lions have a relativly low success rate in hunting, but they try alot, where as pumas are sutle-er and have a very high success rate. But if you want to do patronuses, then I would have the opposite, so George's would be a lion, and Fred's would be a puma.