Therein lies my point though. Characters who are corrupt or evil simply because they are don't tend to make for convincing characters. Why are they power hungry freaks?

Also, if the world turning to rubble and making everyone their slaves is their plan, do they believe they will have omnipotent powers? Because unless this world is very small, ruling it with two people would be impossible. There would be too many rebellions and such.

Now, this concept would work brilliantly if you want to use it to show how skewed the parents' view of the world is. If you're going to go about it like that, I think you should keep the 'world turning to rubble and everyone being their slaves' just the way it is. It could be a great tool.