The Stranger pulled back his hand, and Madara's heart came out with it. That heart was a withered thing, he noted, having shriveled from disuse. Its absence was no great loss; it had stopped beating many years ago.
No, the loss of his heart was merely a sentimental concern at this point. The lower half of his torso that had been ripped apart and tossed aside into a dark corner of the immense cavern bothered him more. Now, the half that he had left lay slumped and ragged in his crude stone throne.
Fighting had been fierce at first. The Rinnegan possessed many powers, including absolute control of attractive and repulsive forces. Unfortunately, it did not easily pierce the smoke bombs the invader had brought with him, and Madara's muscles had long since withered away to nothing. He had been forced to rely on two of his helpers instead, and they had not been sufficient defense. Not against this man.
The red-coated Stranger stroked his luxurious black mustache, looking ludicrously out-of-place in the smoky, dimly-lit cavern. It really was an outfit meant for the sea, after all.
"You're pretty tough for a mummy," said the Stranger, "Normally this kind of brutality is beneath me, but you just don't seem to want to die."
"Then stop," said the Old Man, the noise raspy and dry as he fought not to cough. "You have nothing to gain... from my death... What about... a trade? You must be looking for something... if you've broken through the barrier placed... by the Sage of Six Paths... I can help you find it."
The Stranger chuckled. "You're of no help to anyone now, wretched ghost. Look at you- wasted, broken, too scared to die properly. So you hang on, and for what?! Whatever it was, old man, the world doesn't need you anymore. I bet you would have been a real terror fifty years ago, but now? Now is your last chance to smile as you go to your death."
With a single swipe of his sword the Stranger cut the cables that had kept Madara functioning even when his body had ceased to truly live. Despite everything, Madara couldn't quite manage to feel angry. He had once been a man consumed with rage, but those emotions had broken down long ago, the responsible chemicals in his brain decaying away as the unnatural decades passed.
The black form of Zetsu, his most trustworthy servant and his will made manifest, lay crumpled and shredded upon the ground, dissolving into dust even as they spoke. How he had died the Old Man couldn't say. Black Zetsu had taken far more severe damage in the past to no effect. The other, lesser, White Zetsu had been even more thoroughly obliterated. Only one other of his helpers remained now.
Would it have made the difference? Would Tobi's presence have saved him? He doubted it. This fight was over from the moment the Stranger had discovered his hiding place. He could have fought the red-coated Stranger himself, if he had been anything more than an old, withered husk, but now…
The cables cut, Uchiha Madara died quietly, the foreign chakra that had sustained him leaving his body.
Still, he resolved one day to return.
The Stranger left the cavernous hall the way he had come, picking his way across the rocky remains of the shattered boulder that had once blocked the entrance. He traveled swiftly back to camp, his vibrant coat contrasting with the earthen colors of the forest.
The Confidante met him before he got there, stepping alongside the Stranger to match his pace.
"Roger?" asked the Confidante, the question clear.
The Stranger in the red coat grinned from ear to ear. "The Poneglyph was right- we're on the right track. 'The Sage of Six Paths.' We know what we're looking for now, Rayleigh."
Later, a twisted creature with pure-white skin returned to Madara's lair carrying the body of a young boy from Konoha. He was shocked speechless by the carnage that had been wrought before him. He had only been gone for twenty minutes at most.
Now his master and his brothers lay dead. He could have helped fight, but instead he had been busy saving a useless child. The boy that Tobi had brought with him, Uchiha Obito, had been partially crushed by a tremendous boulder and would surely die without his aid, but it all seemed so unimportant now.
Dropping the boy, Tobi collapsed to his knees, kicking up the dust of decades.
He couldn't even cry. It was just one of the many bodily functions that he was incapable of performing. He was nothing but a lump of functional pseudo-flesh that existed to carry out his master's whims- how could he have any hope of fulfilling Madara's plans without the help of his brothers?
After a minute, Tobi turned to regard the young Uchiha child. Unconscious. With great effort, Tobi poured himself into the task of healing the boy, using his unique cells based on the stock of the legendary First Hokage of Konoha. It hadn't really been explained to him just why that man's cells worked the way they did, but he'd always sort of pictured the ancient Hokage as a sort of weird, blobby, meat-monster.
The young boy's flesh, bone, and brain were rebuilt before Tobi's very eyes as his own body filled in the pieces- repairing, reconnecting, and extrapolating. Pulse recovered, breathing restarted, blood pressure climbing, everything was looking good. But then everything went wrong. Tobi felt it with a strange certainty, as if the child's body were speaking to him. With skillful hands he unwrapped the child's flesh and bone to expose the material underneath, and he could see that the brain was dead. He had waited too long, and now too much of it had unraveled from lack of blood flow.
Again, he wanted to cry. The plan that Lord Madara and big-brother Zetsu had concocted was tremendous in scope- far too much for Tobi to handle alone. The kid could have helped see the plan through to completion, if he had survived...
Tobi stared at the form of the brain-dead child. He stared at the brain, and at the wrinkles, and twists, and folds of his cortex. The boy's brain really looked a lot like Tobi's own body, he considered. Swirly, and lumpy, and… and...
Wait a minute…
With a rising, bewildered hope, Tobi uncoiled the white pseudo-flesh of his own hands and merged with the brain once more, tendrils reaching out to encompass and meld with each cell. He invaded, overwrote, and assimilated. As he reached the brain-stem, he felt it.
It was a distinct sense of... Yeeeurgghh...
Tobi had never felt Yeeeurgghh before.
Tobi had never been more excited in his life.
-Two Years Later-
-Cavern Underneath The Land of Earth-
Silence reigned in the underground cavern. There was no movement of air. Even noise was alien to this place. In nearly a thousand years, the sanctity of its isolation had only been breached once. No water, fungus, or even bacteria lived in the perfect, sterile dust of the cave. There was no light, after all- none whatsoever. In its center sat a dark, stone tablet, etched with numerous strange and indecipherable glyphs.
Then, suddenly, there was a man in the room. The dust, long settled into a motionless retirement, shook itself awake and danced around the room, the air pressure increasing from the sudden arrival of extra matter in the sealed cavern. That air was stale, as if only begrudgingly allowing itself to be breathed. It had had a nice gig, sitting peacefully in the cavern for a thousand years, not being respired by all sorts of organic creatures.
Tobi didn't care for the plight of the air. He breathed grandly and with great fulfillment. In fact, he let out a small fart just because he finally could.
The immense stone slab in the center of the room remained unmoved by these antics.
Tobi, robed in black, approached the stone. He wore a wooden mask that looked like driftwood, warped and twisted on one side, bleached almost white by the sun and salt. A tribute to a departed brother.
After a time, Tobi removed the mask. Though it was completely dark, Tobi's eyes now saw much more than mere light. He could view the etchings on the stone with perfect clarity.
His face was that of the child he had stolen it from. Not only his face was childlike, but the expressions it wore were still filled with innocent and unfiltered emotions. Tobi had discovered early on that the mask he wore was necessary to prevent people from reading him like an open book. A real face was so expressive, and he just hadn't had enough practice yet at concealing his feelings. Besides, the eyes tended to startle people.
Both of his eyes showed the concentric circle pattern of Madara's Rinnegan.
His chakra flowed out from his body, washing in waves over the room, and his eyes picked up all of its reflections, tracing the contours of each surface, and the carvings of the rough stone slab before him. Despite the perfect darkness, he saw the room painted in shades of his own energy.
Tobi scanned the tablet in the center of the room very carefully. There was no doubt that this was what the Stranger had been searching for. It certainly wasn't in any language he was familiar with, but he felt a sort of itching sensation behind his eyeballs as he read it. When he let that feeling go, the Rinnegan started pulsing with chakra and interpreting the tablet on its own, shoving the data back down the optic nerve.
This was almost certainly what Lord Madara had meant when he had spoken of the legendary eyes deciphering the stone tablets of the Uchiha Clan. That meant that this was another, similar relic. Madara and big-brother Black Zetsu had felt these tablets were terribly important, but unfortunately they'd rarely involved him in their plotting.
Tobi read the stone carefully. And read. And read. And continued reading. There really was a lot there.
On the stone was written a strange, almost unbelievable story. It spoke of a Divine Tree, which he knew about already. It spoke of a fruit borne every thousand years, which he had also known about. He had paid some attention, after all!
It was just… the rest of it that seemed a bit strange.
Tobi stood transfixed by the story for what seemed like hours.
One thing was for certain. Lord Madara hadn't known about any of this. The plan, as it was, had been as such: Gather power, and then use that power to seal away the nine Tailed Beasts inside the Gedo Statue, one-by-one, in the proper order. Once all nine had been captured, use the Rinnegan to resurrect Madara, allowing him to become the Jinchuuriki for the combined being of the Ten-Tails. In doing so, the Ten-Tails would take a form like the legendary Divine Tree. Madara would recover his eyes, and, with the aid of that tree, bind the world in an Eternal Tsukuyomi, an unending illusion that would grant peace and a true heaven to every living being.
Honestly, it had all seemed a little complicated.
This tablet suggested that all of that planning had been a waste. According to this, the real tree was still out there, which was so incredibly strange. Black Zetsu had been absolutely clear that the only way to do this was to hunt down the Tailed-Beasts. If Madara had known that the original Divine Tree was still around, surely he would have tried to find it and use it to implement the Eye of the Moon strategy?
In fact, if he worked the numbers on the tablet a bit, it looked like it had been almost exactly a thousand years since the last time the Divine Tree had bloomed.
This was really heartening. Tobi had really been stressed about getting that whole Tailed-Beast thing worked out. Tobi had already tried to follow the plan, but had gotten a bit confused and gone after the Nine-Tails first, which had been totally the wrong order! People were still pretty angry about that. Doesn't everyone make mistakes? Also, he still wasn't exactly certain why Lord Madara hadn't wanted to be revived from the dead until his plan was nearing completion.
Well, whatever. This new plan seemed like a much better option to him anyway. There was just one problem.
Tobi sighed, his face deepening into an exaggerated frown of sheer sorrow.
He really didn't know where that tree was. The tablet didn't say. He only knew that it wasn't in the Elemental Kingdoms. Since it wasn't here, even searching for it would be nigh impossible. Everyone knew there was no way to leave the island chain that contained the entirety of ninja culture.
"It's not fair!" Tobi shouted, echoing in the cavern. The air, which had been souring rapidly as the visitor overstayed his welcome, vibrated indignantly from the disturbance. "Every time I think I have a good plan there's always some stupid reason it won't work!"
Then he saw it. There was something else carved into the floor beside the tablet. It was so shallow he almost hadn't seen it at all, like the writer had struggled to chisel into the tough-seeming stone.
I knew it was true. The Tree is the source of it all, and the Celestial Dragons keep it safe at their throne of power.
I have come so far for this fragment of the truth, and I will carry this passage with me to the island at the very end of the world.
-Gol D. Roger
What an unusual name, thought Tobi.
Thank you for starting this story. As befits Naruto and One Piece there are going to be lots of explosive and sometimes goofy battles, strange adventures, and unusual characters. Despite this first chapter, the story largely takes place from the perspectives of Naruto, Sasuke, and any others on the Going Merry.
On the Naruto side, it contains Troll-Tobi, Akatsuki on a boat, mid-timeskip Team-7, Sasuke with a past that made him a little kinder, and more focus on mid-level battles.
On the One Piece side there are no character changes from canon. For them, it takes place immediately after leaving Alabasta.
For all parties, teamwork will be absolutely crucial.
Action-wise, I am skipping all 'which universe would win' arguments and just balancing the characters under the same power-system. The combat is intended to be satisfying and intense, not a power-fantasy curb-stomp unless that's the only way it makes sense in-universe.