In the Hero of Ages, book three of the Mistborn Trilogy by Brandon Sanderson, there are two gods which rule over Scadrial, the world in which the series takes place. The first god, Preservation, seeks to create stability and eliminate chaos and change. Her counterpart, Ruin, strives for the opposite: complete destruction and disorder. For millennia, the two were locked in stalemate, with neither able to achieve their extreme goals.
On one hand, each knew that only by working together could they create. On the other hand, both knew that they would never have complete satisfaction in what they created. Preservation would not be able to keep things perfect and unchanging, and Ruin would not be able to destroy completely. (pp. 472-473).
In the series, especially in book three, Ruin acts as the primary antagonist. Considering this, it might be easy to mistake Ruin for a god of evil. This, however, isn’t true, and that’s something I find very interesting. Despite being a cause of great distress for the world of Scadrial and the heroes in it, Ruin cannot be fully destroyed– he does not represent evil, but rather change. Without him, Preservation would just as easily destroy the world as it was. The only difference is that where Ruin would dissolve Scadrial into a state of chaos, Preservation would keep it captive in a state of everlasting perpetuity. Truly, neither extreme is a good option– the world needs a balance of change and stability. The Hero of Ages takes place at a time in which Ruin has gained more power than Preservation, and thus he is who the heroes must fight against, and as mutual enemies of Ruin, they naturally become allied with Preservation. It is important to recognize, though, that the circumstances have made one god into an ally and the other into an enemy. The roles could easily be reversed, with the heroes of Scadrial fighting to not be caught in a world where no change can be inflicted. Though it is still more interesting to have villains with more complexity than seeking an absolute, the concept of chaos and stability being the absolutes rather than evil and good is still at least somewhat more compelling.