The Dragons

The final decision before The Scission would be complete and the gods departed from the physical world, would be the creation of the Dragons to serve as guardians of Tre'Novis and its inhabitants in their absence. 
Those Dragons of metallic coloring were created by The Favored  while the chromatic were created by The Forsaken. The chromatic dragons were not always evil as they are now, but without the influence of the gods, their neutrality of their nature went unchecked, and eventually they became the wicked creatures they are today.