Quote Originally Posted by Kawaii Ryűkishi
When they lost their homeworld, the Lunarians decided that they could populate the Blue Planet, but since it was already occupied by humans who had a quaint little civilization going for themselves, they decided the polite thing to do would be to sleep in the Lunar Subterrane until they had petered out.
I seem to remember that the Lunarians were planning to make contact with the humans when their civillization had advanced to the state that the Lunarians were, and co-exist with humanity, rather than wait for the humans to wipe themselves out. Correct me if I'm wrong, but that's just what I remember FuSoYa saying.

As for Zemus, I always thought that he was developed through (SPOILER)Golbez.