You will encounter various “secondary” enemy factions on the different planets during your conquests. You can of course destroy them to seize control of the territories they have occupied, but you could also rally them to your cause and exploit their units and special abilities.
Organized into clans, micro societies ruled by ultra-violence bordering on barbarism, Raiders make their presence known on each of the deposit planets. Only a lack of unity and cohesion has so far prevented the Raider clans from claiming any status as a great power, but anyone who could subdue and unify the clans would have some serious shock troops to deploy in the etherium war.
Dangerous creatures that feed on etherium, the Parasites infest certain of the deposit planets. While most agree that their total eradication would be the best course of action, certain scientists advocate studying them, arguing that it would be possible to control them and use them as a weapon; one that would cut down any opponents without hesitation.
Guardians are autonomous drones with limited AI. Refusing any communication whatsoever, they defend the old, devastated colonies of a race that has clearly been extinct for millennia with ruthless efficiency. Anyone who could reprogram, and therefore control them, would have a formidable argument to bring out onto the battlefield...