The basis for my game's mythology was such. Stars versus Suns. Two races, fates inextricably linked in death, life, and rebirth, and three(or four) worlds. The world before, the world they inhabit, and the world they will reinherit.
The pilots don't know this, but the earth they inhabit is a lie. See, earth died a long time ago due to bombardment by AT Waves, which caused horrible, terminal dissolution of self(tanging).
The world they live in is a complicated simulation in a failed terraforming/escape project known as the "Red Egg", that never left Earth. The Kachina(angels) are artificial intelligences who have taken the identities and self-awareness of men to properly foster a world in which simulated personalities can metabiologically evolve to one day resist the effects of AT Waves. They know that their mission failed before it began. They also know that even if they succeeded, they'd die. They were created as nothing more than sacrifices. Gods of governance of lesser importance.
To this end, they've tormented humanity as Angels. This simultaneously satisfies their urge for justice, as well as driving humanity towards spiritual evolution through conflict. The world the pilots know only really began 17 years ago during Second Impact. Everyone's memories from times before are hazy or nonexistant.
The pilots themselves were created in a situation that mirrors the Kachina's. They were part of a large-scale eugenics project by NERV to create a generation of synch-positive Eva pilots, whose lives were intentionally made crappy in order to foster synch-positivity, which is strongest when rebelling, due to the urge to define yourself.