Maybe the Void is some kind of emptiness-beyond-the-worlds, and OblivAeon spawned from it somehow, or is a manifestation of a part of its power that "went rogue" or something, and these Oblivion Shard thingys are bits of the void that have fallen through or broken off other creatures that spawned from there at other times, or something? Maybe the Void is actually some kind of entity and was the one that lost the "Nothing will happen" bet that spawned the Wager Master. Or something :D.