Well the Maou was waiting for the Hero because that's what always happened. The Hero sets out to kill the Demon King and considering the power of a Hero they would always make it pretty far. She just wanted to walk a different path from all the other demons kings ( as far as I know )

But I found it intriguing that the Spirit of Light was green and that it slowly zoomed out to show the sun in the demon world. So would that mean that the Spirit is their Sun?