Her role there was to oversee the cloaking device that the Star Empire had installed on the USS Defiant and to make sure it was not misused. She later joined the Defiant on its mission into the Gamma Quadrant to make contact with the Founders of the Dominion. After the Jem'Hadar managed to detect the cloaked Defiant, they boarded the starship and T'Rul was hit by weapons fire.
Along with the senior staff of the Defiant, she was taken to the Founders' homeworld and placed in Borath's elaborate simulation. In it, she was incensed that the Romulans had been excluded from peace talks with the Dominion. T'Rul was later rescued after Kira Nerys and Odo discovered the room where the simulation was being held. (DS9 episode & novelization: The Search)
In 2374, she was assigned to Project Blue Sky and worked with Jadzia Dax to create an enzyme to alter the genetic profile of the Jem'Hadar. (DS9 - Prophecy and Change short story: "The Devil You Know")
In an alternate reality, T'Rul remained aboard DS9 for at least several months. In 2371, Federation and Dominion delegations met on Deep Space 9 to negotiate a treaty in response to the Dominion's peace overtures in 2371. However, during the talks, Odo was murdered with a phaser. Consequently, the negotiations broke down and the Dominion launched an attack on DS9. Although the Federation forces were eventually able to push the Jem'Hadar back through the Bajoran wormhole, DS9 suffered significant damage and heavy casualties. She assisted Chief Miles O'Brien in repairing the station.
While posing as his murdered counterpart, the Odo of the primary universe accused T'Rul of staging the attack on him in order to derail the peace talks. He argued that a Federation-Dominion alliance would have been disastrous for the Romulan Empire, which would have been forced into an alliance with Bajor. T'Rul strenuously denied the accusation, claiming that it was unfounded. Odo retorted that while it may be untrue, it was far from unfounded. He later determined that the alternate Major Kira Nerys was responsible for killing the other Odo as she feared the consequences for Bajor if the Federation and Bajor were to form an alliance. (DS9 comic: "The Looking Glass War")
- DS9 episode & novelization: The Search
- DS9 - Prophecy and Change short story: "The Devil You Know"
- DS9 comic: "The Looking Glass War" (alternate reality)