Ahdar Ru'afo was the leader of the nomadic Son'a people, who attempted to oust the Ba'ku people from their homeworld in 2375.
Attempted takeover
Born Ro'tin of the Ba'ku, Ru'afo became disenfranchised with the simple life that the other inhabitants of the colony endorsed, and led a group in an attempted takeover of the settlement. Ru'afo was eventually foiled, and he and his compatriots were exiled from the planet, becoming the Son'a. Over the course of the next century, the Son'a built up their military forces, and even conquered two primitive races, the Tarlac and the Ellora, integrating them into their society as a labor class.
The Son'a soon found, however, that in the absence of the metaphasic radiation being emitted from the rings of their planet, the aging process began to take its toll, and they became obsessed with recapturing their youth, undergoing numerous medical procedures to rejuvinate themselves and maintain a younger appearance. By the 24th century, Ru'afo initiated a plot to take revenge on those who had banished him, and harvest the metaphasic radiation with which to reinvigorate the Son'a.
Alliance with Starfleet
In 2375, Ru'afo entered into an alliance with Starfleet admiral Matthew Dougherty in order to facilitate the Ba'ku's forced relocation from their planet in the area of space known as "the Briar Patch." According to their agreement, Starfleet would covertly transport the Ba'ku from their colony in a Starfleet holoship, and the Son'a would subsequently perform a procedure on the planet's rings to collect the metaphasic particles, leaving the planet uninhabitable. Ru'afo convinced Dougherty that the technology which would evolve from the alliance would be of a great benefit to the Federation, particularly due to the hardships suffered by them during their then-ongoing war with the Dominion, but actively kept from him the fact that the Son'a and the Ba'ku were the same race. Eventually, however, their plot was uncovered by Jean-Luc Picard, captain of the USS Enterprise NCC-1701-E. As Picard and a group of his officers remained on the planet in an effort to defend the Ba'ku, Picard's first officer, Commander Will Riker, attempted to reach the perimeter of the Briar Patch to inform the Federation Council of the details of Dougherty's plot. Knowing that, if the Federation were to become aware of the Starfleet plan for the forced relocation of a peaceful people, they would be unable to proceed, Ru'afo managed to convince Dougherty to authorize the deployment of two Son'a ships to intercept the Enterprise. Ultimately, however, Riker was successful in defending the Enterprise against the Son'a attack, and Picard was able to protect the Ba'ku. When Picard informed Dougherty of his discovery that Ru'afo was simply trying to gain revenge on those that had exiled them, Dougherty attempted to put an end to the mission, a decision to which Ru'afo responded by killing him.
Picard and Ru'afo witness the destruction of the collector
Ru'afo eventually decided to activate the Son'a collector, a vessel designed to collect the metaphasic particles, while the Ba'ku were still on the planet, an act which would have resulted in the deaths of all life on the surface. Picard managed to win over Ru'afo's second-in-command, Gallatin, who deactivated the collector and transported Ru'afo and his bridge crew to the holoship. Ru'afo, however, was able to beam aboard the Collector alone and re-start the launch sequence.
To stop him, Picard boarded and attempted to activate the self-destruct. Ru'afo attempted to kill Picard, but Picard was able to avoid his attack long enough to attain his objective. As Picard activated the self-destruct, the vessel began to explode around the two of them. Although Picard was beamed aboard the Enterprise, Ru'afo was killed in the destruction of the collector. (Star Trek: Insurrection)