Perhaps as old as time itself, Bill Cipher has scoured the multiverse as a chaotic entity of destruction. Its sole purpose is to manipulate others into doing what seems to be menial tasks, only to build up to the ultimate goal. A sadistic existence where he will have complete control of the laws of physics. To him, it would be but a simple party. But to mortals that exist within, would be a never ending hell.
While cheerful and seemingly willing and eager to help, Bill is far from trustworthy. Eventually after working through his deals, those whom accept his offers and assist him will soon realize just how twisted this ancient entity is. At one point, some early humans would have gone as far as calling him a god of chaos and death.
Whatever his case may be, Bill's plans are his own. And he keeps his grand scheme secret up until the very end. And at one point, while traveling the cosmos, Bill did find one human willing to aid his schemes. While masquerading as a benevolent being, Bill offered a deal. While this human was allowed to know knowledge beyond what any other had ever even thought of, Bill was able to enter his mind to use him for his own selfish schemes. For a time it worked, until this human was able to figure out what he was planning and put a stop to it. He sealed himself away along with Bill in hopes that his home, Earth, would be safe from an inevitable apocalypse.
For decades, Bill would remain trapped in this realm until he was unwittingly released by a child. Now free he was finally allowed to continue his schemes.