Fiesty: Because he's an aggressive little guy with a big ego.
Apache: He looks like a living Native American headdress, with feathers and all.
Kotori: "Screech Owl Spirit". I just liked it, and he does remind me of a little spirit. NN is Koti.
Pandora: It's just a name that's stuck to her, though I just call her Pandy.
Aurelius: Because he looks like gold with all that yellow and those sparkling metallic scales. Reyli is what I call him mostly.
Waldo: Where is he? Yes, he looks like Waldo from Where's Waldo. Also, since he's a marble, I'm sure his colour will change to who knows what.