I actually met an extremely rare diaperfur who kept it to himself and never told anyone, and I asked why he was into that. He said something about wanting to be a kid again, when you don't have any real worries in the world. I get the feeling that Darlal is just taking that idea to the extreme, just without wearing diapers and using them in real life. Think about it, he constantly eats sugar cereal, is all about childish things, acts childish, etc. He's someone who either doesn't want to grow up (beyond what the average person feels) or simply can't come to terms with the fact that he's no longer a kid, so he simply acts as if he never aged beyond whatever year of his life he chose to be nostalgic about.
