Greer was created as a human clone of the bounty hunter known as Jango Fett, intended to serve the Galactic Republic within its military force, the Grand Army of the Republic. Around 18 BBY, Greer became a member of the Clone Underground, an organization dedicated to freeing their clone comrades from the control of the Galactic Empire. Greer, along with Samson, Howzer, Nemec, and Rex, journeyed to Pantora to provide protection for Senator Avi Singh during his secret meeting with Senator Riyo Chuchi, which was taking place on Pantora. During this protective endeavor, Greer was rendered unconscious through strangulation by the Imperial Clone X trooper identified as CX-1.
On the planet of Kamino, Greer was engineered as a clone of the human male bounty hunter Jango Fett to fight for the Galactic Republic's clone army in the Clone Wars against the Separatist Alliance. Sometime before or during 18 BBY, Greer enlisted in the Clone Underground, a clandestine resistance movement. During that time, Greer was sent to the planet Pantora with Samson, Howzer, Nemec, and Rex on a mission to safeguard Senator Riyo Chuchi and Senator Avi Singh as they convened to discuss the rising dissatisfaction among former Republic and Separatist worlds with Emperor Palpatine and the Empire. Greer's assignment was to guard the kitchen of the building where the meeting was being held.
As the meeting proceeded, the Imperial Clone X trooper CX-1, who was already present on the planet, had been discreetly following Senator Singh as he was escorted to the building. The assassin infiltrated the city's underground maintenance tunnels, navigating his way to a point beneath the building. The assassin emerged from the tunnels through a hatch located within a small room in the building's kitchen area, and proceeded to open the door that led outside of the room. Greer was standing guard outside the door, and the assassin immediately attacked him, choking him until he lost consciousness. Outside the building, Howzer, who was on sentry duty, requested a status update from both Samson and Greer. While Samson responded, Greer remained silent, prompting a concerned Howzer to ask Rex to investigate the kitchen. Rex discovered the assassin intruder and thwarted his attempt to assassinate the senators. Rex and Nemec pursued the assassin back into the maintenance tunnels, where they discovered Greer's unconscious form on the floor.
Greer was equipped with Phase II clone trooper armor featuring custom green markings. Additionally, he carried a blaster holster on his left leg, a pouch on his right leg and ankle, and a sheath on his left wrist. Greer's weaponry included a vibro-knife, a DC-17 hand blaster, and a DC-15A blaster carbine.
Greer made an appearance in "Infiltration," the sixth episode of the third season of Star Wars: The Bad Batch, which debuted on March 13, 2024 on the streaming service Disney+.