Before the events of Fight for the Future, there used to be a great number of demigods vying for power within the realms. However, there have only ever been six Upper Deities and above them, a singular Overgod. Ever since the events in F3, all demigods lost their powers and The Six were banned by Ao from directly using their powers to influence the cosmos ever again. However, that does not mean that they are without influence in the mortal realms.
Ao is the only Overgod that exists and presides over all of the other deities in the multiverse and generally remains neutral and uninvolved, but true followers (Aoists) can sometimes contact him or gain his direct blessing. Ao created all time and space as well as the original deities to preside over various realms.
While technically neutral, he does encourage his followers to pursue the path of good, but will not force them to do so since he believes that free will is essential for stability in the multiverse.
He has only appeared on Terra Essentia once, a thousand years ago when he came down in physical form and stopped a tear in the space/time continuum that would have engulfed all of creation in the multiverse. It was at this point that the world became aware of his existence at all and his worshippers were first founded. His physical form was that of a human with dark skin with swirling celestial patterns and flowing white hair standing at 12ft tall and whose eyes were that of stars.
Ao has not been seen since, but his followers pray for his return one day to restore order to the universe once again.
After the dawn of the universe, Ao created six children: Chronos, Fate, Tanabris. Thraxian, Eldath, and Symphonica.
Ao generally takes a fairly hands off approach when it comes to governing the universe, but the biggest benefit of being part of the deific pantheon is the ability to directly petition Ao. Many gods have done this throughout the millennia and Ao has a decent track record of helping his children along in their goals to shape the world.