The aulphax and skeptauri have a complicated relationship. Xenologists have termed them "parallel empires" since their domains mostly overlap with each other.
The aulphax, a species driven by a religious ideology, aim to turn planets into gardens and recruit their sapient inhabitants into their ranks. The skeptauri, a hive-mind of intelligent machines, dismantle planets and asteroids to build megastructures. Colony ships will carry both aulphax and skeptauri to new star systems (along with yan hitchhikers), and the two will mostly stay in their separate spheres, as not all planets can be made habitable. But the friction comes in when the terraforming potential of a planet is ambiguous. The disputes are mostly diplomatic in nature, resolved through debates, but they have been known to fight each other. This combined with the status of the skeptauri as something of a "servant" race means that they are not exactly friendly, despite their interdependence.