Pax was a member of the Grand Army of the Republic as an ARF trooper. He fought during the Clone Wars, a conflict between the Galactic Republic and the Separatist Alliance. In the year 21 BBY, this clone trooper joined Jedi General Mace Windu's Lightning Squadron on a mission to the planet known as Ridlay. During their assignment, they encountered a subterranean species that the locals called "ghosts," as well as the Separatist leader Count Dooku. During a battle against Dooku's B1-series battle droids, the subterranean species threw Pax to his death into the Ascension Well.
A clone of the human male bounty hunter Jango Fett, Pax's creation took place on the planet Kamino, where he was trained as a clone trooper. As an Advanced Recon Force Scout Trooper, Pax fought for the Grand Army of the Republic in the Clone Wars. He was a part of the 91st Mobile Reconnaissance Corps' Lightning Squadron, which was under the command of both Clone Commander Ponds and Jedi General Mace Windu.
In the year 21 BBY, Pax, along with Windu, Ponds, and fellow clone troopers Heater and Razor (both ARF troopers), embarked on a mission to the planet Ridlay. The purpose of the mission was to investigate why the planet had stopped communicating. The Lightning Squadron arrived on Ridlay's surface in an LAAT gunship and began searching for the planet's inhabitants. They moved through the shadowy, forested environment and eventually discovered an abandoned village. Ponds then sensed movement coming from the trees, which caused the squadron to gather behind Windu.
A local named Agon came out of the trees, warning them to run because the "ghosts" were coming. Soon after, numerous creatures appeared, and Pax and the rest of the Lightning Squadron began to fire at them. After realizing that their blaster fire passed right through the "ghosts," they retreated to the shelter where Agon's people were hiding. There, they learned that these "ghosts" appeared every fifty years during a total eclipse, but this time, they were aggressive. The squadron went to the Ascension Well, a large opening from which the "ghosts" emerged, to find out why they were aggressive. At the well, three "ghosts" came out of the depths, and Pax and the others started shooting at them until Windu ordered them to stop. Windu sensed the conflict within the creatures, and then the reason for their aggression appeared: Count Dooku, the leader of the Separatists.
As the "ghosts" began to approach, Pax and the other clones started firing at the incoming waves of B1-series battle droids. Because blaster fire could not stop them, several "ghosts" overpowered Pax, solidifying just enough to take his weapon and grab him. They then threw Pax down the Ascension Well, where he screamed as he fell to his death. Ponds was shaken by Pax's death and shouted out in response. Despite Pax's death, the Lightning Squadron was able to defeat Dooku's forces and restore the "ghosts" to their peaceful state.
Like all clone troopers, Kaminoan scientists implanted Pax with a behavioral modification biochip to ensure obedience to specific orders. Pax wore Phase I ARF armor and used a DC-15A blaster carbine.
Pax's first appearance, though unnamed, was in the comic story "Separation Anxiety Part One," which was in the ninth issue of the 2020 Star Wars Adventures comic series released on September 8, 2021. He was named later in "Separation Anxiety, Part Two," which was in the following issue on September 29 of that same year. Both stories were written by Michael Moreci, with Pax drawn by Michael Avon-Oeming and published by IDW Publishing.