The idea here is to make pirates fit into the lore without having to do too much new stuff. I don't think pirates-as-barbarians fits into an otherwise very well meshed universe, and could instead be an interesting feature of the universe.


Imagine that pirates are the raiding ships of an uncommunicative race,  which inhabits black holes and only wants exotic resources, with no interest in planetary systems (or ability to survive there for long). That means most pirate attributes apply (no diplomacy, raids, random spawning) but you could make them more of a real NPC faction. this is in the vein of the Xeelee (from Steven Baxter's books, which I heartily recommend).


The endless would have maintained a non-intervention approach with this faction. You'd have the pirates and Endless seeing each other as mosquitoes, an annoyance to be adapted around but otherwise left alone. 


This would make the pirates behave in  unique and game-enriching ways:

  • Pirates fleets could jump between black holes
  • Pirates would raid for resources, to be taken to a black hole, not send combat fleets (preferring to take convoy ships mid-flight)
  • Ships would be stolen/repurposed rather than destroyed
  • Pirate fleets would be small numbers of low CP but high-tech ships
  • Possibility of co-operative anti pirate quests, hunting their base of operations in the galaxy
  • Pirates could escape areas to harass other empires, stopping them from getting caught in a small region
  • Defeating pirates would grant exotic resources
  • Pirates would need to return to a planetless system to fill up on low-gravity juice (or whatever allows them to get away from the black holes).