It is the root of his grudge, stuck to the end of his wrist. The root of all that went wrong, from which grows the one thing he's powerless to set right. The growth that bears the fruit of his betrayal...
The golden hook serves Crocodile well in combat and can be tolerated out of it. On bad days, when treating it like a natural part of his body becomes too much trouble to bother with, he feels tempted to let go of it – when he's alone, when no one else can see. To do so means having to face something that weighs more than all the metal in the hook.
It's the loss it reminds him of. It represents far too many things lost to the sea. He has heard older pirates say: There's no end to tears on this side of the Grand Line, but the New World will dry them all. And hasn't he dried out completely by now? Utterly deserted by his tears. The joke is far too stupid to be funny, and he grins around his cigar precisely because it can't force any genuine amusement out of him.
And back to that New World he goes, once more with ambition; that right there is something that keeps rearing its ugly head no matter how many times he stomps it out. Doing it for his own good, really, and now for that of his first mate. Now that one's a keeper. Understands the importance of self-control. Yes, Daz Bones is ready to enter the New World with him. And Crocodile, having learned his lesson, is ready for the loss of him.
Trust is overrated, after all. Trust a crewmate to throw you to the wolves or get himself killed. Thinking back to his old crew, Crocodile inevitably remembers the lost battle against Whitebeard and the mutiny afterwards. Things had been going wrong long before that, the humiliation had been the final straw. Friendship was not enough. With friends like that... Crocodile hopes they had time to enjoy the wealth they got at his expense; their end was certainly nasty enough to wipe off all memory of that once he got back to them.
That damn hook weighs a ton. Crocodile removes it, eyes turned away. That's not something he wants to remember, not now. Not ever. And still it's a wound he must keep picking at, won't let the scar tissue do its job and let things heal with time. It's a lesson he can't afford to forget. In this world, it falls to you to protect your own pathetic heart, and if you can't...
The door opens and closes with barely a sound, his first mate's arrival nevertheless announced by his greeting. Welcome home. Aloud, Crocodile acknowledges his presence with a grunt and shifts on the bed, left side facing the wall. Daz sees the hook unattached and understands immediately. His eyes turn away before the rest of his body follows, and off he goes to mind his own business. Definitely one to keep. It will be a sad day when he goes.
That day might come sooner than they think: they've been finding old contacts, hiring capable hands, and the New World seems just round the corner now. New sights to see, new challenges to face... and old enemies to fight, for old times' sake. Crocodile has to smile as he thinks, once more, of the Straw Hat kid with his idiotic resilience, his infuriating crew that still has not been broken by this world. It will be interesting to see how long that lasts. And if it never breaks? Do people like that still exist?
In a sudden burst of anger, Crocodile tears the cigar off his lips in his hurry to crush the still smouldering head on the back of his left hand. The smile turns into a grimace as he thinks of how long it took for the world to first fill his heart and dreams with subtle little cracks, finally pounding away at them with the relentless fury of the elements, the sea does love to watch those nails get hammered down... The cigar hovers above his left hand, his right trembling with the need to do this. Straw Hat..!
He once sailed these seas to become the Pirate King. That was in another life, when he was another person who dreamed of a better future on the waves. That person believed in wide skies and blue horizons as far as the eye could see, in the absolute freedom only the one who conquered all the seas of the world could achieve, stop it, Crocodile grinds his teeth together – isn't that disgustingly like something the Straw Hat kid would believe in? In the freedom of the open sea, in freedom among all the nations in it? The cigar finally comes down on the mark in revenge, to avenge him and his lost heart, but to Crocodile it feels more as though the dragon's hoof comes alive again, eating its way into his hand in fond remembrance of the day it ended his dream.
For this mark you can hide. This mark you can certainly keep hidden. Do what you will to it; the imprint it leaves beneath your skin and flesh and bones is the important part, the one that makes sure you will never be free again. The dragon soars by treading on the backs of those who are no longer human.
His rage gone cold, Crocodile wipes the ash off the back of his hand and puts his hook back on before the worst happens and Daz sees what it hides. That has happened before, with different people. In all his years as a pirate, it has become quite clear to Crocodile that when faced with the choice between him and the world, the world is not the one they turn their backs to.
Of course, it's different for... He twists the hook and it bites into his wrist. The thought goes away – for a moment. If a brat like that can inspire such loyalty in his crew and friends, then could Crocodile as well...
In his mind, he curses Straw Hat Luffy a thousand times for doing this to him, for infecting him with hope. The dream is over, let it go. And yet, a new dream persistently oozes out of his withered core and spawns unwanted life where he has let everything die. It's unrealistic, nothing worth reaching for, but his hand clamps down on the base of the hook and cannot stop trembling. He's not as rational as he used to be, and it takes hold within him whether he allows it or not. If I could reach that high...
If he could one day dry the waters of this mighty sea, to slay this dragon, wouldn't the freedom in that act be enough? Crocodile closes his eyes as if in pain. It has been so many years. So many. Should he conquer these memories, wouldn't the brand enslaving him to them become powerless?
Yes.
And that day, not fearing the eyes that might see, he would cast off his hook and watch the mark, without meaning, fade under the sun; just one scar among many, another sign of a battle that was not able to kill him.
...
Well, that was that. Obviously I made up the lot of it while waiting for Oda to give us the official Crocodile backstory... (Also, I guess Mr.1 should be called by his given name like everybody else, but I usually see him referred to as Daz and went with the flow.)