Thats, uh, kinda exactly what I did, but I didn't know about the forgetful fog (thought that was a toa pod thing... or something...). I just said I was thinking about the backstory as if they were from Karda Nui. Any other place that was centrally united, with somewhat advanced technology would work. A better way to state Casanuva and Vakua's backstories is this: both hail from a different place, someplace with a higher level of tech and civilization, where matoran are the primary race. Neither know (anymore, at least) where they came from or why they showed up, but they remember some elements from their past (Casanuva never wanted to be a Toa, Vakua learned to cope with his mask, etc)