Before all others, there was the Earthmother. The first, and for a long time, only, entity formed by the process of merging essence.
An entity of pure, untainted Earthpower, the Earthmother sought only to create life, and to that end, Gaea was created, with the Earthmother merging with, and adopting the name of her creation.
Over the course of many millennia, powerful entities sought to replicate the feat of the Earthmother. Such an undertaking however required almost impossible reservoirs of Earthpower, which could only be gathered over the passage of time, and was increasingly difficult with the growing number of clustered entities, each having developed ego, and seeking to consolidate their own strength and achieve further growth, rather than unifying and risking possible suppression.
As the Earthmother before them, these entities, Titans, as they titled themselves, adopted the name of, and merged with, their creations, inviting outsiders from other realms to create life, ensuring their own survival. On completion of their creation though, the Titan entered a permanent state of hibernation called the Titansleep, losing direct influence over their respective worlds. Thus, the Multiverse was created.