He assisted Goss in incapacitating the Federation negotiator Mendoza by placing pyrocytes from the DaiMon's own blood on his palm in order to infect him when he and Goss shook hands. He and Kol later took a shuttle into the wormhole, accompanying the shuttlepod Ley from the USS Enterprise-D. Despite warnings that the wormhole had taken the two vessels to the Delta Quadrant instead of the Gamma Quadrant as it was expected to, Arridor refused to follow the Starfleet shuttlepod back through the wormhole. Moments after the shuttlepod entered the wormhole, its terminus changed, leaving Arridor and Kol stranded in the Delta Quadrant. (TNG: "The Price")
Arridor and Kol eventually made their way to the homeworld of the Takarians. They found out about a legend on the planet, told through what was called the Song of the Sages, in which gods were to come to the planet. They passed themselves off as the Holy Sages, he the "Great Sage", and, under this guise, Arridor and Kol obtained vast wealth by demanding tribute from the Takarians over the next seven years. They appointed people to collect dues, such as Kafar, from the various regions and tracked their "earnings" regularly.
In 2373, the planet was visited by the USS Voyager. Arridor was able to make it difficult for the crew to oust them, successfully pointing out that the crew can't simply abduct them from the planet. Arridor was fooled by Neelix, posing first as the Grand Proxy to the Grand Nagus, and then as the Holy Pilgrim of the Takarian legend.
Unbeknownst to Arridor, the last verse of the Song of the Sages detailed the Sages' departure from the Takarians. Arridor and Kol were captured by Voyager, but soon escaped in their shuttle and attempted to return to Takar but were instead pulled into the Barzan wormhole, making it even more unstable. (VOY: "False Profits")