Rex honestly isn't expecting the strike that explodes stars across his vision. He lashes out instinctively in reply as he falls, his kick clipping his opponent's hip, but it's too late.
They were pretty evenly matched in hand-to-hand, always, but Rex has been on the run since the fall of the Republic, the rise of the 'Empire." Despite their best efforts they've all been eating half rations at best, and if nothing else can be said for the Empire, they keep their fighting force in good shape.
All that, and still Rex only goes down so easily because Cody has the element of surprise.
Surprise, because he should have been pumped with enough tranquilizers to down a bantha for a month — so, at least enough to get the high metabolism of a clone trooper through the next day unconscious while the bacta healed him and Rex transported him from the clandestine medical facility to a more secure base.
Surprise, because Cody's eyes are blank, his face twisted in a rictus of hate as he comes after Rex.
Surprise, because Nap already removed Cody's chip. Yet there is no recognition, no spark of Cody in those eyes, despite the distinctive scar beside his eye.
Immediately after surgery, Cody had come to briefly, warm golden-brown eyes fixing on him blearily. "Rex?" He'd rasped, eyes flicking around hazily, not focusing well, but locking back in on Rex long enough for Rex to laugh tearily and say "Glad you're back with us, Cody," before they closed again as unconsciousness took him.
Now his eyes are wrong, cold amber instead of warm gold.
They look like Sith eyes.
"Cody, what are you doing?" Rex yelled, heart in his throat and choking his words, twisting out of the way of the next blow, but the first was well aimed and Rex can fell his balance wavering, the blow to his unprotected head effecting his coordination, the followup blow to his thigh making him stagger.
Cody didn't answer him, didn't even seem to hear him.
What new, Sith-born devilry was this?
Rex got a few blows in as well, but he was already compromised, and there was no recognition of pain in Cody's eyes or face. He didn't even falter when Rex lashed out. He felt at least a few of Cody's ribs give under the brutal kick.
Nothing. Nothing was going to stop him. He just came on, relentless, and Rex had no room to maneuver in the little sleeping room of the ship.
"Cody," Rex tried again, dodging out of the way of another attack. "Cody, please, stop this, this isn't you. It's me, Rex. Cody, it's Rex, stop this, come back to me."
There was none of Cody's efficient grace in the movements, only brutal force. Rex had fought against Cody countless times, sparred for fun and pleasure until they knew each other's moves by heart, until it was far more a dance than a fight, but that knowledge worked against him now. Every time instinct tried to anticipate Cody's movements, he was wrong. He took another blow. Each wore him down, his stamina not what it had been, and no match for a strength Cody had never possessed before.
What had been done to him?
"Cody, you have to fight this, whatever it is. You know me, it's Rex, remember me, I don't want to fight you!"
Then a tackle sent him sprawling to the ground, and Rex just managed to get a hand around Cody's wrist before the blade of his own knife, stolen from his hip, slashed towards his throat. Muscles straining to hold Cody up and off of him, he stared into Cody's blank face.
Cody looked at him, but didn't *know* him, didn't recognize him, didn't know anything but the determination to see Rex dead. His weight bore down and Rex's strength gave just a hair. A line of ice sprung up along his throat – he felt the knife blade part his skin.
"Cody, please!" Rex begged, not able to kick up and dislodge the other, too thoroughly pinned. So he begged, but not for his own life. He didn't want to die, not now, not like this, but he would not beg to be spared. He would beg for Cody. For Cody's sanity, and life, and to prevent the inevitable, Rex knew, if Cody managed to come back to himself, to find himself sprayed with Rex's blood, found Rex dead at his hands.
"Cody, Cody, please," Tears choked his voice, even as his hands slipped more on Cody's wrist: sweat and fatigue, and no, no! What had they done to Cody?! "You have to snap out of this, you have to remember me! You have to remember yourself!"
Pain, hot and bright, liquid seared down the skin of his throat.
"Riddur!"