They were lovers and geniuses, two of the greatest military and administrative minds humanity had ever produced. They knew the art of war; they knew how to run a province; they knew when to please a populace, and when to wield an iron first.
They were the ones chosen to carry out humanity's greatest need, the primordial urge of survival. Astronomers, biologists and astrophysicists had finally gathered enough information to calculate the exact odds of life being born anywhere in the galaxy. Humanity stood at a crossroads, at a point where it might still have enough time to reach out and establish a firm foothold across the galaxy. Were it to delay, alien civilizations might spring up all around it, making humankind only one minor player among many.
They were solicited for the task of leading the colonization wave, and they both eagerly volunteered. Both of them were frozen down, their brains then carefully cut into microscope-thin slices. Delicate robotic hands handled the slices, feeding them into machines that scanned them and constructed accurate models of the original brains.
They were installed on the triply-protected and secured mainframes of each colonization ship. Every ship was a small behemoth, equipped with self-replicating probes and rows upon rows of cloning chambers. Each was fully equipped to build a new world, establish a foothold on any planet that possessed a solid surface.
They were the first ones to awaken, whenever one of the ships was approaching its destination world. Though of no biological relation, they now became siblings of a kind, their cloned bodies growing in a shared machine womb. As they grew, nanomachines imprinted their developing brains with memories and skills, inherited from their old lives.
They were fully grown as they emerged from their wombs, physically and mentally adults. They walked naked in the halls of the great ships, empty at first. Together, they studied the initial reports of the first probes sent ahead to survey the worlds their ships were approaching. They made plans, and they watched as their crew was being grown, in thousands upon thousands of tanks on each ship.
They were the ones orchestrating all the details of the initial landing, and beyond. They led the ships to settle barren, lifeless worlds; planets filled with lethal gases; planets covered entirely with water. Some systems had no planets you could make a landfall on. On those they were quick to extract raw materials from asteroids, harness the energy of the local star, and establish harvesting stations in the atmospheres of the gas giants. Humanity, albeit unable to walk in a planetary gravity, prospered in those systems as well.
They were born again and again, on the approaches to a million systems. And each ship contained within the blueprints for building another ship, just like it. When they had secured a foothold and established a basic industry, they would soon begin to fabricate new vessels, for reaching out to the next worlds. They updated the mainframes of the new ships with the experiences and lessons the colonization of this world had taught them, and then sent them off, wishing their mind-siblings all the best.
They were eventually met by aliens, just as humanity had feared. The settlement waves had been many and numerous, each launching the next wave as soon as human technology allowed. As human technology had improved, the knowledge of it spread by light speed via radio, and the colonies had began to launch their new fleets faster yet. But it had not been enough to overrun all other life, and many aliens had developed on their own. The aliens had perceived the human expansion wave, and had been determined not to be run over.
They were forced into battle, thousands and thousands of times. Sometimes they had a ready colony before the aliens came; sometimes they were intercepted in interstellar space, before reaching their destination.
They were now leading the ships of the tenth, twentieth, thirtieth waves, by now well experienced and accustomed to interstellar life. They fought with a calculated ruthlessness they had been chosen for, reprogramming the production lines on their ships to squeeze out fighters and weapons. If victory required cannibalizing crucial components that meant leaving the ships stranded or the colony starving, then so be it. The distress call had already been sent, and the rest of humanity was already aware of their plight. Whether help arrived in time was irrelevant, the important thing was that more resources were being mustered for battle.
They were slain a hundred times, a thousand, ten thousand. They fell fighting green-skinned aliens, aliens that had been transformed into nothing but machines, aliens that embraced biological technology. Most of the time, they knew in advance when the missiles would hit and when they would die, and could do so in each others' arms. They embraced each other tight, and died together as they had been born together.
It did not matter. They had done what they were meant to do, spread humanity across the stars. For each dying colony, burning under an alien sky, there were a million more. For every instance of them that died, a million others remained alive, coordinating the retaliatory strike. For every vessel that the aliens built, humanity had the resources to build a hundred million, enough to drown all opposition.