Born Gal'na of the Ba'ku, Gallatin was friends with Ro'tin, the Ba'ku who would later be known as Ru'afo. In the 23rd century, Gallatin assisted Ru'afo in attempting to take over the Ba'ku colony on a planet in the area of space known as "the Briar Patch." 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.
In the year 2375, Ru'afo and Gallatin entered into an alliance with Starfleet admiral Dougherty aimed at covertly relocating the Ba'ku from their homeworld and harvesting the metaphasic radiation from the planet's rings which continually rejuvenated the Ba'ku's cellular structure. When Ru'afo, who was obsessed with gaining revenge on those that had exiled them a century earlier, decided to step up the plan and perform the procedure while the planet was still inhabited, an action which would result in the deaths of all the Ba'ku, Gallatin became disenchanted with the plan, and was subsequently convinced by Jean-Luc Picard to help him stop Ru'afo. In that capacity, Gallatin assisted Picard in contacting his officers to initiate a plot to beam Ru'afo and his bridge crew to a holoship, where they would be unaware that they were in a simulation. Gallatin, Picard, and Lieutenant Commander Worf were subsequently able to take control of the bridge, but Gallatin and Worf were later taken prisoner by the ship's crew as Picard beamed aboard the Son'a collector ship to destroy it. Gallatin and Worf were freed, however, when the ship's life support system was destroyed by the crew of the USS Enterprise-E, leaving the Son'a with no choice but to surrender.
After the conclusion of the crisis and the death of Ru'afo, Gallatin returned to the planet's surface, where he was reunited with his mother, a meeting arranged by Captain Picard in an effort to begin the healing process between the Son'a and the Ba'ku. (Star Trek: Insurrection)