The Oumen Saga
In the late Pleistocene era, an alien modifies two primitive humans with nanotechnology granting them effective immortality, before unexpectedly having to abandon them alone on his spaceship. They and their descendents go on to become the inspiration behind the various pantheons of ancient Earth mythologies. Of particular note among them are Xio and Met, once lovers until, on the questionable advice of his father Kron and grandfather Oron, Xio reluctantly "murdered" Met to prevent their unborn child from overthrowing their rule of the Pantheon the way they had overthrown Kron and Kron had overthrown Oron before. But because of their immortality, this "murder" had to be done in a way that left Xio literally haunted by the furious still-living mind of Met, trapped within his own mind, for the rest of his immortal life; while their unborn daughter Aten assumed control of Met's still-living body and in time usurped leadership of the Pantheon just as Xio's forefathers had foretold. All of them stranded on Earth from when they crash their spaceship a mere few generations into their lives, this Pantheon spend millennia wandering the world, shaping a course of history that turns out to be alternate but parallel to our own, before eventually reconvening into a secret society called only the Foundation, that develops space flight centuries in advance of the rest of humanity, and continues to shape world history from above thereafter. (More details).
Hundreds of years into the future, Earth is united in a network of world governance called the Internation, while the last remnants of the old United Nations retain control of only the Lunar colonies. These powers vie for control of Mars' growing colonies, against the influence of a Martian crime syndicate controlled, unbeknownst to anyone but the Foundation, by Kron and those of the old Pantheon most loyal to him, who fled to Mars to escape the Foundation's scrutiny of Earth. Against this backdrop, Xio and Aten work together to raise a clone of Met and slowly imbue her with the original Met's memories up to the point of her murder, to finally right that ancient injustice. This clone of Met reaches maturity and fully learns of her origins just as matters with Mars reach a climax, and Kron's Martian forces feign an attack on Earth to distract from their flight through the artificial wormhole that the aliens who made them immortal, the Ehrban, left behind. This plus a mutual misunderstanding with the Ehrban results in an immediate war with them, and consequently the setting-aside of differences between Kron and the Foundation to fight that war, and the public revelation of the Foundation to guide humanity in this time of crisis. That war is soon put to rest thanks to the return of an earlier Foundation exploratory ship that had already met the Ehrban; only to be quickly supplanted by the spillover from a war the Ehrban were already fighting against different aliens, who were the cause of their abandonment of Earth thousands of years ago. In the ensuing conflict Earth's moon is shattered, and as pieces of it rain destruction down on Earth, both Xio and Met, mutually trying to save each other, are separately buried under mountains of debris in the ruins of a dying Earth, and presumed dead. (More details).
Thousands of years later, Met's body is uncovered by erosion, and the nanotechnology in it restores her to life. Her memories, both of her original life and of her second, slowly return to her in a confusing jumble, and she explores the rewilded landscape of this postapocalyptic Earth and the primitive remnants of humanity who survive on it, slowly rising to prominence as the central figure in its ongoing history thanks in no small part to her obvious invulnerability and immortality. As she searches the world for signs of Xio, whom she remembers now only as her lost love, and who she figures must have survived if she did, she finds not all the surviving remnants of humanity are quite as primitive as those of the area she awoke in, and eventually mediates the escalating conflict between two powerful rival factions, reuniting the people of Earth at last. As they set out to rebuild civilization to the heights that she remembers, still searching for Xio all the while, they discover that remants of advanced technology remain in other parts of the solar system not destroyed by the war, and that even more advanced remnants of humanity itself — namely parts of the Foundation, now lead by Kron, with technology far in advance of even the old Ehrban — survive outside the solar system, to the reconciliation with whom Met guides her new Earth. And then at long last she discovers the body of her long lost Xio, still alive inside a facility now buried under literal mountains of stone, but trapped inside his own mind now, so as to sustain what he believed to be the last remants of humanity inside an old virtual world kept operational only by its connection to his immortal body. (More details).