Humanoid, spacefaring culture preoccupied with materialism and often anti-aging methods, discovered by Starfleet in 2375 to be not a unique species but an offshoot of the Ba'ku. Originally nonaligned, the exposure of the Son'a's true nature introduced Prime Directive interference concerns and broke up a joint Federation-Son'a relocation of the Ba'ku so as to safely mine the dense metaphasic rings around their adopted world in the "Briar Patch" for their de-aging properties. The ambitious Son'a faction under Adhar Ru'afo had falsely portrayed itself as a unique culture after fleeing a failed coup attempt some 50 years before the Enterprise-E crew got involved, and built itself into a nonaligned military power.
Although Captain Picard made strides to reunite the estranged and aged Son'a with their youthful Bak'u parents as the Federation made their lush world a protectorate, the Son'a still chose within a year to became a client of the enemy during the Dominion War. The Son'a ketracel-white facility at Devos II supplied the Dominion with the addicitive nutrient required by its Jem'Hadar troops.