Born of the same primal power as the First Gods, the Phoenix Force exists close to the heart of reality itself-- the Source. The light of the Phoenix Force is the Power Cosmic, and the power of the Phoenix is nearly absolute, as it exists in a state of perfect harmony with itself and the universe.
Before time was time, before Oa broke the First Firmament into the fragmented multiverses, the lone universe filled with teeming life, only to collapse and expand again in a cycle with infinite iterations, lost in an infinity of timelines.
Among these were the residents of the planet Taa, a race of supremely powerful and technologically advanced organic life. From these survivors, the Phoenix picked one to be the 'legacy' of the last living beings of that universe.
This individual was named Galan, and in exchange for his life, he was bound to serve the Phoenix as the ideological embodiment of predatory hunger. His name-- Galactus.