'Twas a fine summer afternoon in a spring island, a docile and calm place somewhere in the middle of the New World. It was a small place, largely covered in jungles and mountains, with nothing of particular interest to anyone in particular - apart from its fine wine, perhaps.
Yet now it had acquired most of the attention of the Marines, and the World Government, with twelve battleships surrounding it, ready to fire at a moment's notice. For even though the island itself was not of any particular notice, it currently held two of some of the most powerful men in the entire world - the sort of men the Marines, for a very good reason, did not ever wish to be even on very good terms with each other, let alone have a friendly meeting.
"Our intelligence confirms that the Red-Hair entered the island four days ago, and has not been seen leaving," said the den den mushi, in the distinctive voice of the vice-admiral Doberman. "We have located the ship of the Straw Hat Pirates as well, so it appears that your report of them landing has some truth in it, Smoker."
"I have been chasing them for months," vice-admiral Smoker growled. "I would not have mistaken in such a matter. Is there any word on exactly what they are doing yet?"
"Mmh... none whatsoever: it appears they are being very secretive. But we have uncovered some other disturbing intel..."
"What is it?"
"Our intelligence has confirmed that Red-Hair Shanks was present in Straw Hat Luffy's hometown some twelve years ago, keeping it as a home base for a while." The voice sounded concerned. "This is very much not the first time those two have met: they have been acquaintances for over a decade. Even then they may have laid the foundation to their grand schemes and plans!"
The fellow officer remained silent in contemplation for some time, puffing his cigar. "...Are you sure they would have had something planned?", he finally said. "Straw-Hat would have been very young at the time of their first meeting."
"There is a precedent in dangerous young criminals: Nico Robin, the Devil Child, was no older than eight when she became a notorious outlaw," Doberman reminded. "Besides, they could have begun the true planning only later on. And even if they have not, they are close friends, and this cannot be good for any of us."
"Hrrm," Smoker murmured in an agreement. "As soon as we have any reasonable information of their strengths and plans, we will make our move. He has been elusive, but we will finally capture him, after all these years."
"But we cannot wait for too long... who knows what deadly plots and preparations they are doing even now? I cannot bear to think about it."
Thanks to his stretching powers, it was no feat at all for Straw-Hat Luffy to stuff seventeen watermelons and twenty-two hunks of meat into his mouth at once. But since no one else was capable of such, it made for a great party trick.
The reunion of old friends, idols, and in one case father and son, is an excuse for a grand feast unlike any other. Old acquaintances were reforged, new friendships made, and much fun was had by all. Indeed, in all their jubilation, there were naught but two people on the entire island that still gave even the slightest consideration to the veritable army of Marines currently parked right outside the island.
But should either Nami or Ben Beckman ever attempt to voice these concerns, the response would be essentially to just stop worrying and chill out. "We will deal with the matter when the time comes for it," Shanks reassured both. "For now the time is not for that, but rather for party and fun!"
And so it had been, for everybody present listened to this man. He was a party animal unlike any other, and Luffy had clearly picked up a few traits from him, although he was more focused on the part about eating. Put together, their free-spiritedness was, indeed, more than enough to get the rest of them to that mood and to worry about tomorrow.
But it all ended as quickly as it had started, if not even more so. Not because of the Marines, but rather because of something Luffy did: he chose this as the moment to take off his straw hat, and gracefully hand it over to Shanks.
"Ah, yes...", Shanks smiled happily. "I believe we did have a deal of that sort."
"I'm a great pirate now, aren't I?", Luffy asked, likewise smiling.
"Yup. You're one of the finest pirates I have ever had the pleasure to meet. But that hat is yours now: you don't need to return it." He lifted his hand in a gesture of declinal. "Go ahead and keep it."
And that should have been the end of it. In any reasonable pirate crew, between any two level-headed pirates, it would have stopped right there and then. Luffy would have put his hat back on, smiled, and they would have returned to partying. Unfortunately, these two were not anything of that sort: certainly they were both some of the most powerful men in the world, with the wisdom and cunning to match - but they were also, when it really came down to it, some of the biggest numb-skulled idiots to roam the seas.
And so Luffy did not put his hat back on, but rather continue on offering it for Shanks. "Look, I promised I'd return this hat for you. And I'm gonna."
"And I keep telling you, you don't need to."
"No really, I insist. I can't just keep this thing now, not anymore."
"Well, I insist too. Just forget about it." Both men were still smiling, but it turned into something somewhat strained, perhaps even hostile, as the inane argument continued far longer than it should have. They kept it up for a little longer after which Luffy, having had enough, simply tried to place the hat on the red-haired pirate captain's head.
"Guys, maybe if you just-", Nami attempted, but was promptly ignored, as Luffy tried to put the hat on Shanks again again, but the other dodged, then eventually grabbed the other's hand with his to block it. The younger pirate instinctively punched, which Shanks kicked aside, along with the rest of him.
And then, the next thing Luffy did with his straw hat was, quite possibly, the worst thing he could ever have done with it in Nami's mind: he threw it for her, and she caught it almost instinctively, colour fading away from her face. "You have got to be kidding me about this...", she whined, mostly to herself.
They most certainly were not. Shanks slowly drew his blade and pointed it at Luffy, who charged at him, flexing his muscle to get the blood flowing much faster, painting him red and smoking, prepared for the battle.
When the two clashed, the very ground of the island shook under them all, not that the two would have noticed that. It was a cloudy day, yet in an instant every single one of them was cleared out of the sky, displaying the evening sun well, bathing the battlefield in golden light. As a fist was barely blocked by a sword, the shockwave sent many trees behind them flying. As the blade's counter-attack was dodged by the length of a hair, the jungle was cut apart in a single neat stroke.
And so begun the incident that would be later known as the War for That Bloody Hat.
The picking up of the winds could be felt all the way at Smoker's ship, and he could see trees being levelled, smoke cloud rising, and flocks of birds fleeing from whatever was going on.
"Sir!", captain Tashigi reported, with a den den mushi open for further reconnaissance. "It would appear that the captains Luffy and Shanks have apparently come to a... disagreement... over some thing or another: they haven't figured out what it was yet."
"Good for us," Smoker contemplated. "It appears they may not have been as staunch allies as we first thought." He turned his attention fully to her, and the rest of the Marines on the ship. "Be prepared: as soon as one of the two is incapacitated, we will attack!"
The plethora of yessirs was suddenly cut out when a mast collapsed. Nobody had seen what had struck it, although it rather looked like something had stretched very, very thin and far from the island, before being snapped back. "What the flying f-"
"That does it!", Smoker called out to the den den mushi. "Smoker to all ships: we will attack now!"
A barrage of cannon fire struck the island and awakened the pirates to a new threat being thrown against them... except for two. Other than those particulars, the rest took immediate action, leaving the two idiots to deal with their thing for a while in order to defend themselves, and their friends, from a common enemy.
Even as the battle raged around them, Luffy and Shanks could not really afford to pay any attention to any of it. Considering their respective levels of power, even the slightest drop of concentration could very well have deadly results: even while cannonballs exploded around them, even as Marines landed and fought their comrades, even as a mysterious smoke attempted to whisk Luffy away, not even once did their attention slip from one another.
They were almost equal in terms of combat ability. The Red-Hair was, of course, of the Pirate King's original crew, and worthy of every bit of fame that position had brought him. But the Straw-Hat had come a long way since their last meeting: he had trained with Shanks's old first mate, then proceeded to develop even further by himself, in a truly astronomic speed. Neither could get an edge over the other.
The war lasted either three days and nights, or ten minutes, depending on the interpretation. The first of the Marine ships was sunk even before any of them could make landing, and the rest were routed very quickly afterwards, and sent packing in a humiliating defeat. But the duel that had started it all, the battle over the straw hat and returning it, took much longer - and ended with a mutual knock-out, Shanks's sword making a gaping wound on Luffy even as his fist scored a hit on the other's jaw, both men falling down to the ground, next to each other.
Luffy was the first to recover, so to speak. The following morning, he simply lifted one hand, and called Nami's name: she returned his hat for him, and he unceremoniously planted it on Shanks's face, who did not react.
It took another day for either of them to be in any sort of a shape to even speak, let alone sit up. Both had gained extensive injuries in the fight, by the way of sword and fist, and had come close to dying. Their respective crews would have berated them if they had not been so worried.
This time it was Shanks that spoke first. "Hey."
"Did you know... this hat used to belong to Roger before me?"
"Huh? Really?" Luffy took this information fairly well, though it may have been he had not the strength to really yell out how awesome it was.
"Yup." He picked up the hat from his face... then gave it back to Luffy. "Here. This time it's yours for the keeping."
"Oh. Thanks," he responded, with a casual smile, as if this was the most natural thing in the world.
This earned both of them a punch from their first mate and navigator, powerful enough to send them in full coma for three more days. When they woke up, they would have a lesson about needlessly complicating stupid things.