Disclaimer: I own nothing recognizable from One Piece as far as chapter 485.
Warnings: Spoilers for chapter 485. You have been warned.
A First Mate's Loyalty
Over the time that Zoro had sailed with Luffy, under Luffy's command, he had come to respect the boy more and more with every day they lived through, every battle they fought, every adventure they had, every sea they sailed, and every breath they breathed.
Since that fateful day when Luffy had stormed the marine base to get Zoro to join him and avenge Coby's crushed dream, Zoro had done nothing but follow Luffy, watch Luffy, listen to Luffy and obey Luffy. Zoro owed Luffy his life who knew how many times over, and Zoro was a man who was always conscious of his debts and promises.
Yet it was not because of that 'debt' that he was always first to leap into the sea after Luffy when he fell. It was not because Luffy had saved Zoro who knew how many times at risk to himself that Zoro had not hesitated to place himself in front of Luffy when poisoned darts were headed at Luffy and they were both unarmed. It was not because he aspired to be stronger that the greater the risk, the quicker he was to try to protect his captain. In fact, Zoro himself couldn't explain it.
But sometimes Zoro was last to move when Luffy was in danger. Sometimes Zoro looked on expressionlessly as Luffy was pummeled and burned and frozen and bloodied. Sometimes, Zoro paid so little attention to Luffy's imminent demise that casual observers wondered if he cared at all about his captain; if he would be happy to see his captain die.
Indeed, Zoro's attitude seemed contradictory to most. Zoro was a man who refused to submit or to follow—he was one of the freest of independent spirits—yet within a few hours of meeting Luffy, he was quietly submitting to the boy with the straw hat and calling him Captain. Zoro had run towards the penalty stand with blood-shot eyes when Luffy was nearly beheaded, yet when Luffy was subject to explosion after explosion in a fight with Foxy, Zoro had watched without batting an eye. If Luffy fell into the sea, Zoro panicked and dove after him without wasting a moment—even when they had been fighting fishmen and Zoro was mortally wounded, he had been fully prepared to leap into the salt water for his captain though it surely meant his own death—yet when Luffy was nowhere in sight and had not been for a while, Zoro did not worry at all.
To Zoro, however, this made perfect sense. He himself was not and would never be able to compare with Luffy in any way. So when it was just a matter of Luffy's power, or interference would mean defying Luffy's commands or compromising Luffy's honor, Zoro just watched; at times he even walked away. But if Luffy was helpless—in the water, or unable to move—and there was no chance of Luffy making it out of the danger, it was then that Zoro stepped in regardless of circumstance, because from that moment when Luffy had leapt in front of him to take the bullets that would have killed Zoro but had no effect on Luffy, Zoro had known that Luffy was a greater man than he would ever be, and his life was worth a hundred of Zoro's.
Zoro's faith in Luffy was unwavering, but even Luffy was helpless at times: when he fell into the sea, when he was pinned to the ground, when he was unconscious after a battle, when he was protecting something dear to him and moving would mean its loss… So when Zoro deemed it fit, he stepped in.
That was why he stepped forward before Bartholomew Kuma when the man came to take Luffy's head. While Zoro had no doubt that Luffy could have defeated the psycho, Luffy was already unconscious and so it was Zoro's duty to protect him. Sure, there were the others; but no matter what Usopp claimed, Zoro was Luffy's first mate, and when Luffy wasn't available, it was Zoro who had to take charge.
And take charge he did. He fought with all he had. But it was not enough.
So Zoro tossed his swords—his soul, his promises, everything he'd ever lived for—to the ground at Kuma's feet and offered his own head. Zoro had never dreamed that he would willingly give his life, but he realized that that was only because he'd never dreamed that his captain's life could ever be in jeopardy this way.
Sanji had tried to stop Zoro and give his own life for his captain instead, but Zoro wouldn't allow it. Sanji went about it all wrong: he tried to sell himself by making himself sound greater than Luffy. While Zoro acknowledged his effort, that was proof to Zoro that Sanji could not lay down his life for Luffy, not here and now, because Luffy deserved to have someone who fully acknowledged the greatness of the man called Monkey D. Luffy. No matter what anyone said, Zoro would be the first and only one to lay down his life for their captain. Besides, Luffy would die anyway if he lost all his comrades.
Zoro supposed he should be grateful that Kuma had decided to simply give him Luffy's suffering rather than take his life. Because the moment that a tiny shred—just one tiny little shred of the huge bubble of suffering—became his, Zoro screamed. It confirmed to Zoro what he had always known—that Luffy was a greater man than he could ever be.
At that moment, Zoro knew that now more than ever he couldn't let Luffy die. Luffy would journey further out into the world and become Pirate King. There wouldn't be a man who could bring him down unless Luffy allowed it.
And Zoro knew that Luffy loved each and every one of his comrades, himself included, and this incredible suffering that he felt that was Luffy's would amplify if he died. By taking Luffy's suffering and living through it, Zoro was not only taking the suffering that Luffy already felt, but also saving him from further suffering.
That was why Zoro refused to lose consciousness; refused to scream again; refused to fall. Because he loved Luffy like a brother, and was loyal to him as any ideal first mate was loyal to his captain, and refused to let him suffer if he could help it.
Luffy would figure out the truth, Zoro knew. After all, contrary to popular belief, Luffy was one of the more intelligent people in the world where his comrades were concerned. Luffy would glare, accuse him, and possibly even skip meals to sit by his sickbed if Zoro collapsed.
But in the end, Luffy was released of this tremendous suffering, and Zoro could carry some of his captain's burden, just this once.
Zoro couldn't ask for more.