The Universe is a strange and wonderful place, most people believe that it is nothing more but dead Space filled with stars and planets but the Universe is alive. It is a living thing, maybe not in the same way any human is alive but alive in a far more advanced way, the Universe is filled with life, billions of stars and Planets therefore the Universe in that way is too a living thing.
The Universe is also held within a balance, a fine line between good and evil. Everyone has it within them, a balance of both good and evil. No matter how good a person is there is always a hint of evil within them even if it is small it is there.
This was the case for one Ron Stoppable, who became cursed with having his evil sound awakened and personified in the form of Nor. Eventually it was the love Ron had for Kim Possible which allowed him to purify his evil side and regain control of his mind and body.
What no one knew at the time was that no good is without evil and when Ron disposed with his evil that great balance which keeps the Universe alive was threatened, for balance to be maintained every living thing within the Universe must be kept within that balance. The Universe being a living enterty then had two choices to make, allow itself to be destroyed in the disbalance or repair the problem, since no living thing would ever wish its self destruction the choice is easy but how could the Universe possibly repair this particular problem?
Simple, by recreating the lost evil, by bringing back Nor!