Fate

"Cainin is unsophisticated, being one of the first worlds pulled by Fate out of the primordial chaos that is the beginning and ending of all things. The art of crafting worlds was not yet refined at this creation. Thus, Fate's work is is malformed; a rudimentary example. Fate populated Cainin with Titans, who were given the ability to create Monsters for their own amusement. The Titans habitually attempted to outdo one another other with the uniqueness and malevolence of their creations. Monsters rampaged across the face of the world, destroying and being destroyed."

Fate is the personification of Determinism. Fate is the primum movens of the Worldbreaker Cycle. Fate created the First, granting him (and likely nothing else) Free Will. Fate also created Cainin as well as the Titans. The First opposes Fate by introducing Free Will in the form of souls into the worlds of Fate's creation, allowing the beings there to defy Fate. Doing this on Cainin prompted Fate to Reforge the world.