An alien agency uses the creation of civilizations and the Fermi Paradox as a means of accumulating and collecting valuable resources.
Their "business model" consists of the following steps:
1. Use life-seeding devices to spread basic single-celled life on billions of planets in a target galaxy (i.e. Panspermia)
2. Wait millions or billions of years for life to evolve to sentience on several of these planets.
3. Individual starships then secretly monitor the radio transmissions of these civilizations, once they develop into a technological society. The crew then goes into stasis for millennia at a time, but are brought out of stasis by automated systems when they detect that radio transmissions have ceased.
4. Most industrial civilizations will eventually render themselves extinct through warfare, usually involving weapons of mass destruction (nuclear, biological, etc.) but other times simply overpopulation, depleted resources, and pollution. The progenitor aliens call this "Closure".
5. While the civilization flourished, it extracted most of the construction metals, valuable radioactive elements, and other rare or useful resources from within the planet. Once they have killed themselves off, the silently-observing progenitor-aliens then move in and simply collect these already-extracted resources from the surface. On a net level across an entire galaxy, on a scale of millions of years, this is significantly cheaper than sending out automated drones to directly mine for the resources.
It is illegal to outright invade one of the seeded civilizations, and the progenitor aliens must wait for them to drive themselves into extinction without outside interference. The progenitor-aliens do not manipulate the seeded civilization in any way, nor were they genetically designed with a predisposition to kill each other: the progenitors simply discovered that (according to the Fermi Paradox) most industrial civilizations will drive themselves into extinction before developing interstellar spaceflight. The percentage of civilizations that survive to an interstellar stage is actually so astronomically low that out of billions of planets to choose from, a single survey ship might never encounter one.
Two aliens, Jon and Toku, are on their way to a planet called Earth that they assume has met its demise like all the other planets they have visited. However, after waking from stasis, they find that this is not the case.