The Clone Troopers of Kamino served the Republic Loyally for their entire lives, up until everything changed with the advent of the Empire. Palpatine and Tarkin no longer wanted to spend the money necessary to maintain the Clone army, and instead wanted cheaper and more plentiful natural born stormtroopers… But Palpatine certainly still saw the Value in the clone troopers, appointing serveral of them to very important positions that he couldn’t trust to stormtroopers…
So this tale begins long after the fall of the REpublic and the rise of the Empire, in the year 14 BBY. During this time, the Free Ryloth Movement led by Hera’s father Cham Syndulla begins causing deep trouble for Palpatine the Empire. Tensions get so high on the planet, that Cham Syndulla actually destroys a destroyer called the Perilous over Ryloth, believing that Vader and Palpatine were onboard… Cham was actually right about this, but while the destroyer was crumbling, Palpatine and Vader managed to get to an escape shuttle, taking with them only their most trusted guards and Orn Free Taa, the senator for Ryloth… Now among these trusted guards was his Royal Guard Captain, who happened to be a Jango Fett Clone Trooper… The Clone Royal guard sadly was never given a name in the story, so lets keep the tradition going and put a name for him down in the comments…
Regardless, things were looking very grim as Vader, Palpatine and the Clone Royal guard crashlanded the shuttle into the jungles on the planets surface. They had no idea what wild beasts may try to attack them while they were down down here. Thankfully, everyone survived the crash except for one single Royal Guard… This royal guard was an absolute idiot and refused to put his seatbelt on during the escape, so when they crashlanded he was left with both of his legs broken and in severe pain.
At this point, Palpatine was furious with his guard, so he ordered the Clone Royal guard to execute his fellow guard with his weapon. without a single thought of hestiation even entering his mind, the Clone Trooper raised his weapon and executed his fellow guard for his idiocy.