The rate of the Prime civilization’s expansion across its solar system never approached anything like exponential. It would take millennia to occupy and utilize all the resources orbiting the star. But the group immotiles were effectively creatures who could live forever, and many of them were planning for the far future.
MorningLightMountain constructed the first interstellar ship on one of its high-orbit asteroid bases. It was a fusion drive vessel; the Primes with their logical thought processes and observation-based scientific research lacked the mental ability to speculate wildly about such concepts as FTL. With MorningLightMountain8658 on board the starship, it took off toward the nearest star, three and a half light-years away. The mission was supposed to be a reconnaissance, sending back information about the available planets and their suitability for exploitation. MorningLightMountain knew it wouldn’t be able to control MorningLightMountain8658 once the ship was outside the Prime solar system. However, it had deliberately restricted the machinery on board the starship, denying MorningLightMountain8658 the ability to establish any sort of technology-based colony. That should have ensured MorningLightMountain8658 simply scanned the system and returned. MorningLightMountain wasn’t sure what use it would have for another star system, but it couldn’t ignore future possibilities. Knowing what was there would help it determine what to do about other stars. There was the remote option that if the resources of its own star system were completely depleted it could move itself to a new planet entirely, one without any other immotile group to contend with.
The one thing MorningLightMountain, or any other Prime immotile, never expected was to find an alien species. All other animal life had finally been exterminated from the Prime homeworld during the last expansion over the temperate lands. They didn’t think in terms of other intelligences. When MorningLightMountain8658 decelerated insystem, it found an extensive civilization occupying the fourth solid planet. Unfortunately for the natives of the second star system, they were a benign species who advanced themselves through cooperation. Physically, they were trisymmetric, smaller and weaker than a Prime motile. They were also individuals.
The starship might not have had any manufacturing systems on board, but it certainly had weapons. MorningLightMountain8658 subdued a vast area of the new planet with nuclear and kinetic bombardment from orbit, and commandeered what was left of the aliens’ industrial base. It began an extensive research project into the trisymmetric creatures themselves. There was a lot for MorningLightMountain8658 to learn, concepts and ideas that both alarmed and intrigued it. Communication with sound. Reproduction via fertilized eggs. Biology in general, and genetics in particular—a field that provided amazing insights into itself. Research into their own physiology and nature wasn’t something Primes had ever conducted; they’d never had the need. Fiction—that was a strange one. Art. Entertainment. All nonsensical distractions to a Prime.
MorningLightMountain8658 began to build its new territory around the starship landing site, incorporating the useful ideas that the aliens offered up into its traditional concepts. Surviving aliens were treated like motiles, and conscripted to help build the territory. Three years later, the next Prime starship arrived, sent by a different immotile. The firefight that ensued devastated half of the continent where MorningLightMountain8658 had established itself. Neither of the immotiles was damaged. They agreed to an alliance, and divided up the planet.
MorningLightMountain wasn’t surprised when its first starship didn’t return. Interstellar travel was a huge unknown; it expected many setbacks. More starships were already being built in anticipation. None of the starships sent by other immotiles had reported back, either. The starship designs were refined, and new missions launched. All of which were swallowed up by the void between the stars.