Author's Note: A big thank you to Cariel for beta reading this for me!

This scene is more of a what-if that could (but probably didn't) happen during the events of Order 66. Also be warned this is my first time writing as Rex so my apologies in advance if I got his voice/thoughts all wrong.

Order 66 was meant to be the proudest moment of every clone soldier of the 501st. For all of their short lives, they had trained for this moment. To be able to storm the halls of the corrupt, to bring about justice, made Rex's heart swell with pride.

The sound of their boots beating against the durasteel plating echoed off the marble pillars and filled the air with an unspoken sense of foreboding. General Skywalker, his expression stony and dark, led the troops up the stairs and into the main atrium of the Jedi Temple. Rex was right behind him along with the rest of his men.

It humbled the young captain to know that he was to be a part of this great moment in history. General Skywalker--now Lord Vader to them--promised them a victory that history would never forget. Rex had little reason to doubt him.

The Jedi Temple was warmly lit, an ironic welcome to its intruders. If the general noticed its strange beauty, his scarred expression didn't reveal it.

Rex knew enough to know that some sort of alarm would go off with their presence. The scanners of his helmets revealed a variety of movement and approaching figures. It was expected; the Jedi wouldn't leave their stronghold unguarded or unattended.

"Take down every last Jedi traitor! Show no compassion. Show no mercy! Spare no one!

"You have your orders, you know what to do."

The words were meant to invigorate and encourage the troops. Yet upon hearing Anakin's statement, something deep within Rex's gut twisted.

Before he had a chance to register what it was, the Jedi revealed themselves. Instincts took over and orders were given. The strange feeling was shortly forgotten as Rex sought to protect his men while accomplishing his mission.

He didn't ask why they had been ordered to take down the men and women who once commanded them. It wasn't his place. Deep down, he knew the answer.

The Order had grown corrupt and arrogant. They no longer cared for the men who fought under their command or the Republic they swore to protect. Rex had seen it first hand through the treatment of his troops, of their general and his second-in-command. It came as no surprise that evidence was found proving the Jedi involvement to remove the supreme chancellor from power.

The JedI, despite their age, were still in fighting form. Their abilities with the Force made them formidable foes. Rex tried not to dwell on the irony or the strange sense of emptiness that came with the betrayal of camaraderie.

While most of the warriors put up a fight, some chose to defend. It was only at the shouts and cries of children that the captain understand why. However, they weren't here for the younglings or so he believed.

Soon the sound of laser fire was heard and the children's cries fell silent shortly after. Upon removing an elder female warrior, the captain immediately sought out the source of the cries. As he made his way through the halls, Rex carefully side-stepped the lifeless forms of fallen Jedi and clones. There were so many.

He tried not to think of what he was about to walk into nor the fact that one of his friends could have pulled the trigger. The very idea disgusted him beyond any words. Nothing could have prepared the captain for what greeted his eyes upon entering the Council hall.

Bodies of clone troops and Jedi lay strewn about as though they were rag dolls. There was no sign of lightsaber burns or cuts on their armour, no signs of laser burns on the elder warriors either, only their pale, confused expressions belied the truth.
Confused, he took note of the burn marks that decorated the walls of the hall as well as the debris most likely caused by Force attacks. It would appear both the Jedi and the clones had join forces to stop something, or someone else.

But who could they have possibly fought and why?

As Rex took note of the slightly parted Council door that now hung slightly off its hinges. It was covered in laser fire and looked as though an invisible force had attempted to pry it open.

The strange, sinking feeling came over him once more and he paused to clear his thoughts. The answer clearly lay ahead. In silence, he motioned the men who followed him to remain put, but ready.

Approaching with caution, he aimed his weapon and prepared himself for the inevitable. But the attack never came.

Just as he was about to tear open the grand doors, something caused him to pause. He could make out the lone silhouette of their general standing alone, lightsaber in hand. At his feet were the lifeless forms of children. Through the helmet, he could make out their fading heat signatures. Their passing had been swift, but violent.

Their bodies were scattered about, revealing their final attempts to make their escape. Rex's stomach sank to his knees as his normally stoic thoughts struggled to accept the harsh discovery.

Ever since general Skywalker gave the order to remove any and all they encountered during the invasion, Rex couldn't shake the feeling that something was wrong. He had witnessed firsthand Anakin's descent from a level-headed commander to a warrior drunk with bloodlust for some time now.

He had tried to speak of his concerns both to General Kenobi and Skywalker himself. It was always met with denial, or in Anakin's case, threats. For the first time in his short existence, Rex found himself balancing the scales of personal morals and orders.

Glancing behind him, the captain caught sight of his men waiting, poised and ready, to strike upon his command. Could he really go through with this knowing what their general had done and knowing what Skywalker--now Lord Vader--was capable of doing?

Taking a step back, Rex gave a simple signal with the flick of his wrist, ordering his men to quickly and quietly depart. There was nothing left for them here, not anymore. They had their orders, just as Lord Vader had his own. They were not trained to ask questions nor to challenge orders. Doing so meant betrayal and that was one thing they had been programmed never to do.

Yet as he made his way back to the Temple's lower levels, Rex found himself doing the one thing he never imagined he would ever do.

His fingers shook as he began to program a simple message. His thoughts scattered as the demands of duty and his conscience warred within him. It was though every fibre of his being was demanding he resist.

"Captain?

"Captain, what are your orders?"

His second in command's voice sounded a million light years away as Rex struggled to activate his private comm channel. His hands fumbled and felt stiff as though incapable of typing in code that would connect him with the one he sought.

The easiest way to resist a mind probe isn't to fight it or block it. You need to let it pass through you. Just clear your thoughts as though entering a state of meditation.

Falling back on Ahsoka's words, Rex paused in misstep and forced his thoughts to clear as though he were entering a trance-like state. It wasn't the first time he had done this and he knew it wouldn't be the last. It wasn't just about protecting his troops or satisfying his conscience. This time, it was about keeping a personal promise, one that he had made in the early days of her training and career.

Time moved to a crawl as his thoughts cleared, permitting his fingers to move freely across the portable holo-comm on his wrist. The message, though simple, took all of his energy to process, leaving him feeling mentally and physically exhausted as though having just completed a vigorous battle. Without hesitation the message was sent and with it came a new clarity that he hadn't felt before.

"Captain? Captain are you all right?"

Snapping from his thoughts, Rex turned his attentions back to his men. He didn't think about what he had just done or the fact that it could be regarded as a form of treason. They had a mission to accomplish and a Republic to save. There would be time enough later to dwell on acts of defiance and its cost. For now, there were more pressing matters.

With a stern nod, he ordered his troops onward and soon was departing for the training halls where the last of the Jedi warriors fought for their lives and the order they served. Though victory was inevitable, it felt entirely wrong. Yet, even his doubts didn't stop his feet from carrying his body into the sanctums of the Temple. Nor did it prevent his fingers from pulling the trigger of his laser pistol, even on the unarmed.

Though he would never speak of it to anyone, for Rex, Order 66 would always be remembered as a night filled with regrets. However, the warning sent to Vader's former Padawan would never be one of them.