CT-5555 would eventually win renown as an ARC trooper, but his early career wasn’t particularly promising. As a clone cadet on Kamino, Fives was part of Domino Squad with Cutup, Hevy, Echo and Droidbait – and Domino Squad consistently failed its training exercises because the five troopers were unable to work as a team.

Fives and Echo sought to transfer out of the squad, but were persuaded to stay, and helped the Dominos pull together as a team and graduate. They were then assigned to seemingly dull duty at a listening post on one of Rishi’s moons. The routine assignment proved anything but, however, as commando droids invaded the post. Their squadmates died defending the base, but Fives and Echo survived and were inducted into the prestigious 501st Legion.

Fives and Echo returned to Kamino to defend the clone production facilities from a Separatist invasion. The two showed both courage under fire and an ability to improvise, and were awarded with promotions to ARC trooper.

The two were part of a team of clone troopers and Jedi sent to rescue Even Piell and Captain Tarkin from the Citadel, a feared Separatist prison. Echo was killed during the operation, leaving Fives as Domino Squad’s sole survivor. On Umbara, Fives opposed Jedi General Pong Krell’s tactics. Disobeying Krell’s orders, he and two other clones attacked an orbiting Separatist supply ship using stolen Umbaran starfighters. Their plan worked, but Krell ordered them executed – a sentence Fives escaped when the clones rebelled against Krell.

During the fight for Ringo Vinda, Fives watched in horror as the clone trooper Tup murdered Jedi General Tiplar. He accompanied Tup to Kamino for a medical examination, and worked with the droid AZI-3 to investigate what had led to Tup’s breakdown. Fives’ dogged pursuit of the truth would lead him to a frightening secret about the clones’ origins, and result in his death.