The main antagonist of the new Black & White will be your custom character. You will play as the main character, and the custom one. It'll use a similar plot as the first/second black & white, where the world is drained of its colour.
Should I do it as a story, where you can choose which character you want to play as? Or should it be that you play as the main character, then the custom, then it repeats?
I'll definitely have more 'acts' to the levels, so it's not just play as one guy, clear one stage, back to the other.