23, a rookie clone among five others, was chosen to serve alongside Clone Commander Vargus and his team. This team included Falco, an Advanced Recon Force trooper; Splice, the medic; and Dom, the demolitions expert.
23 was picked to accompany Commander Vargus on a mission to locate the 313th Legion, which had disappeared on Ando Prime while conducting a standard assault on a Separatist installation. The group of six rookies, accompanied by Falco, moved ahead to perform reconnaissance. Upon spotting the droid base, Falco proceeded for a closer inspection, instructing the rookies to remain where they were. Approximately an hour later, 18, the sergeant of the rookie contingent, contacted Vargus, who instructed them to await his arrival along with Dom and Splice. Inside the base, they discovered Falco conversing with Clone Commander Cody and Jedi General Obi-Wan Kenobi. A subsequent search of the base led to the discovery of Vylagos, a Skakoan scientist and engineer. Vylagos had constructed a Hyperspace warping device, which had been accidentally activated, transporting the droids and clones to a distant, desolate world in the Outer Rim. The rookies, along with Falco and Dom, then went through the device. Vylagos provided them with a device that, when used, would transport all living beings within a one-kilometer radius back to Ando Prime. General Po Bandis instructed the clones to destroy a Confederacy listening post. Upon arrival, the clones commandeered a droid tank. Falco used it to obliterate the outpost and drove it back to the general, with Dom deploying pulse grenades along the route. Upon their return, the general activated the device, teleporting all the clones back to Ando Prime.
The character of 23 originated in the book The Clone Wars: Decide Your Destiny: The Lost Legion.