Quo, also known as RC-1572, served as a Republic commando within the Galactic Republic's Special Operations Brigade. More specifically, he was a member of Tark Squad, an elite clone commando unit led by Captain Nilo, during 21 BBY. Sarsius Torne, his genetic template and trainer, gave him the nickname Quo, which is the Thyrsian letter representing the number two.
As a Republic commando of the Galactic Republic, RC-1572 chose the name Quo and was part of Tark Squad. However, Quo and his team were actually Thyrsian mercenaries who had been trained by Sun Guards' Sarsius Torne to infiltrate the Grand Army of the Republic. This infiltration was part of an arrangement with Zeta Magnus and Palpatine with the goal of recovering Anakin Skywalker. To maintain control over Quo, a cybernetic control band was implanted in him. In 21 BBY, Quo and his squad, while posing as a relief team, were dispatched to aid Jedi General Obi-Wan Kenobi in the liberation of the planet Skye from Zeta Magnus.
Quo, along with the rest of the liberation force, infiltrated Zeta Magnus' fortress via the subterranean tunnel system of Entyrmion that was located beneath the stronghold. While navigating the cave system, the liberation team was ambushed by several Oskan blood eaters created by Zeta Magnus, resulting in the deaths of numerous S'kytri guides, including their leader, Lord Klarymére of the S'kytri Highland Clans. Using a Class-D detonator, the commando squad eliminated the blood eaters, which Obi-Wan considered an "affront to the force". Upon reaching Zeta Magnus' fortress, Quo and Tark Squad deliberately led the Jedi Commanders into a field of R-TechApp Man Traps. Quo and his squad then revealed their allegiance to Zeta Magnus, abandoning the Jedi Commanders to be tortured by Zeta Magnus and his torture droid. During the conflict within the fortress, Halagad Ventor killed Quo by decapitating him with his Lightsaber.
Like the other members of his squad, Quo was equipped with specialized Katarn-class commando armor with a silver coating. His primary weapon was a DC-17m interchangeable rifle, which included a Grappling spike launcher attachment.