Continuing the discussion from Key to the entries in "Forty Exotic Worlds":
Intelligent aliens in Flat Black all happen to be low-tech or pre-tech autochthonous populations, though the Empire does list contact with high-tech and even space-travelling among its concerns for the future. On some worlds the autochthones were exterminated by the terraforming process, on a few they managed to exterminate the settlers, on the rest they live generally miserable existences, mostly on reservations and in parks. But there are exceptions: PCs have encountered intelligent aliens serving as Imperial officers.
There is an interstellar NGO called the Society for the Prevention of Cruelty to Autochthones, which campaigns in various ways for the rights of alien sophonts and quasi-sophonts.
Convenient FTL travel has allowed the Empire to survey planets more thoroughly than was done in the Age of Colonisation; it has not terraformed nor settled any worlds in the fringe with autochthonous sophonts. The SPCA does not trust the Empire to deal fairly with autochthones in the Fringe, and demands variously that it end its contact programs or that it hand its contact programs over to them.
PCs have dealt with autochthones in three non-canonical adventures.
- Towards the end of the first campaign the PCs forced a group of pirates who had hijacked a liner and fled into the Beyond to crash-land it on a planet, which happened to have a quasi-sophont species on it and a species of autochthones with tech equivalent to classical Rome (but with better ships). The PCs had to manage contact to protect all yhe parties while awaiting rescue.
- One Survey campaign, which ended up with no PC explorers at all, involved the PCs being made prisoner by an alien interstellar state that bit off a lot more than it could chew.
- In “Uninvited Guests”, a Flat Black LARP that I ran at Sydcon in 1998, three of the playable characters were autochthones of the moon Tether land rights to which were the issue.
Since those days I have been convinced that intelligent aliens steal the schtick of humans behaving strangely, and for that reason to play down their presence in the setting. @davidbofinger has also argued that Flat Black ought not to feature formerly-inhabited and formerly-inhabitable worlds where the autochthones extincted themselves or sterilised their worlds.