Following the Kuron theory.
He swings the sword just as the poor creature slices its single clawlike tail across Shiro's stomach.
He lets out a gasp and blood dribbles down his chin, the sword puncturing the lungs of the creature and it lets out a pig like squeal. It's getting darker and harder to stay upright, so he pushed his weight on the sword and it sinks lower into the creature until it hits the stained metal floor, and finally finally finally the creature stops squirming, its mouths still and eyes unseeing.
Blood drips onto his torn rags, and he falls on top of the bloodied body of the innocent alien he just killed.
The last thing he remembers is cries of galra tongue, it's growly language he never got the hang of but his mind stumbles out one last translation.
The champion.
His mouth falls slack, and his chest still.
He doesn't get up again.
He stumbles away from the blow, raising his sword as the much taller and stronger galra strikes again, their blades the only sound in the whole arena.
They were both given orders not to kill the other. Shiro didn't know why, but he figured he was valuable. He remembered fighting in this same room before, but the memories itself are a blur. He doesn't know why.
He ducks, rolls between the legs of the galra, strikes the back of the armored kneecap with his metal hand, before launching to his feet and slamming the flat side of the blade into the galra's back.
Stop.
He stopped. The galra looked angry that the match had been cut short before there was a drop of blood, but Shiro guessed that they were still testing him.
The galra looked terrified, and if Shiro didn't know better he would say that he was more of a kid then a commander. His ear tuffs were furry and eyes a bit too wide and shorter than other galra he'd seen.
"This one isn't as violent as the original. Take him out of his misery. I'll construct another." The guard ordered the kid, several meters taller. The kid's eyes screwed into determination, and lept towards Shiro.
"No! Please-" Shiro barely raised his blade in time before the sword sunk into his nose, thin metal surprisingly heavy, and darkness fell over Shiro once more.
His last thought was remembering that he couldn't speak galran before, much less beg for his life.
He ripped the first monster's throat out with nothing more then his hand, the strange colored blood sizzling away as it came into contact with his glowing palm.
He threw the vulnerable flesh onto the tile, used the creature's body to launch himself at the second, teeth bared and eyes blazing.
A slice across the chest, and then he turned towards the guards at the entrance.
Metal wasn't as satisfying to rip, but throwing the discarded parts into the arena before growling, walking into the center where the first creature's body lay, daring anyone to question him.
He gazed at the flesh he had thrown onto the ground, and without a second thought lifted the scaley meat from the floor and raised it to his mouth.
The crowd of galra let out a moan of disgust as he bit into the flesh, the strange blood dripping down his chin.
Then something like a punch to the head, falling to the floor as the scent of burnt hair stung his nostrils.
Shiro readjusted the grip, ducked behind the column where the alien roared.
They had talked between the bars the past night, and they had a plan.
Shiro would take their life, quickly and painlessly, while making it look like a show so he wouldn't get in trouble later.
He protested greatly, but the old alien just waved their clawed hand. "I am but older than many of you, and I have seen the universe for what it is. Kill me, and end my misery."
"I have lived for not as long as you, but I know that death wouldn't be better than this!" The galran language was the only common they had, and it stumbled across his tongue like a child learning to walk.
But the ancient alien shook their head. "You are a newer model. Newer than anyone here, including the original. You don't know what suffering is yet."
He didn't question the strange wording of the alien, and sat in silence.
(He told himself that he wasn't familiar with the language, but deep down he knew it was more then a faulty translation.)
The alien's claws scraped at the column now, a pained growl rumbling Shiro's bones. He wrapped his hands around the stone, pulled himself a good couple meters above the ground, and launched himself at the back of the alien's neck.
A quick slice. A thick goop covering his hands.
The body of the alien fell.
It was later that night in his cell that Shiro realized he never gotten his name.
It was even later when his thin heart gave out.
A lot of time had passed when Shiro caught his reflection in the mirror of the commander's armor.
He had a tuft of white hair, scars covering his almost bare body, and a thick one across his nose he could feel press into his skin and made it the smallest bit harder to breathe.
The galra doctor had surprisingly gentle hands, that pressed against his pulse point and measured the waist and fit of his body, cleaning the arm before injecting it with something.
He opened his mouth to speak, but the doctor answered his question before he could speak it.
"It strengthens your heart. Last time you were in the arena you were near fatally stabbed, the blade near missing your heart." The doctor tapped one long claw to Shiro's bare chest.
"I don't remember," Shiro murmured. "It's just a blur."
The doctor had an expression of puzzlement before letting a noise escaped his throat. "We'll work on that, then. In the meantime, drink all water we give you."
When he was thrown into the cell only an hour later, he crawled to the center and never got up, coughing red into his hands.
When Zarkon's quintessence passed through his body, it was too weak to handle. He was knocked into a temporal realm, before knocking back out of it several light years away from his teammates. Galaxies away from Voltron.
His body froze in the deep of space, days after he ran out of oxygen.
This time he didn't throw up red, or have scars coat his skin. It was hard to walk, hard to move his body, but he pushed forward.
His hair was longer than the other times, but he didn't care. Any insulation from the cold was welcomed.
He just hoped he didn't die of cold.
He knew every time something traumatic happened, he awoke. He awoke in galra imprisonment, so he hoped it was just some form of healing.
But it wasn't. Not this time.
He held up his hand, powered by the liquid quintessence from his artificial veins.
And looked towards his wounded and bleeding leg, the dried blood ever so slightly stained yellow.
He clasped the hand over it and lit it, yelling as the wound burned to a close.
Then collapsed onto the rocks below him, welcoming the thick blanket of sleep.
This time it would be the last time.
He gritted his teeth and ducked around a corner, into the chambers that were so heavily guarded but yet so familiar to walk down.
He was alone in the room, amidst the body of Zarkon that lay in a healing pod of sorts.
He raised his hand, detached from his body, and with the last bit of quintessence lit it once more.
He pressed it to Zarkon's hand, burnt flesh without a reaction.
Then raised the hand on himself.
When he closed his eyes, it was for the last time.
