Lieutenant Rriarr was a golden-furred male Caitian officer who served in Starfleet in the late 24th century. By 2380, he was assigned as to the USS Titan as a tactical officer.
In 2381, he was on duty when the Titan detected a high power sensor beam emanating from the source of energy bursts they were tracking. The duty officer, Fo Hachesa had Rriarr raise shields as a precaution, thinking they might be a Borg early warning system.
After the Titan made orbit of New Erigol, Rriarr monitored the surface of the dyson sphere surrounding the planet that allowed their shuttlecraft Mance to pass through and later reported its closure; Captain Riker ordered him to monitor for any other changes. Later, former Earth Starfleet Captain Erika Hernandez appeared on the Bridge, causing Rriarr to draw a phaser in automatic response, which was disintegrated instantly.
Captain Hernandez offered to help the Titan escape from New Erigol and the Caeliar, and modified their deflector to open a subspace tunnel to the Azure Nebula. During the transit, Rriarr gripped the side of the tactical console and monitored the high-level hyperphasic radiation inside the tunnel. He also detected soliton pulses from behind as the Caeliar attempted to shut down the tunnel. When they exited at the nebula terminus, Captain Riker ordered Rriarr to have Hernandez escorted to quarters and placed under guard as soon as the turbolifts were functional.
Rriarr was one of the tactical personnel temporarily reassigned to the USS Aventine when it attacked and boarded a Borg scout craft, attempting to secure its vinculum. Rriarr was assigned under team leader Pava Ek'Noor sh'Aqabaa, and took a forward strike position with his TR-116 rifle. A Borg drone came up behind the team and impaled Rriarr, penetrating his combat uniform by sheer force. After his death, Lieutenant Shelley Hutchinson recovered his equipment belt.