If Madara Uchiha Was In One Piece  

Madara Uchiha stepped through the portal and found himself on a strange pirate ship sailing the high seas. Based on the skull-and-crossbones flag, he deduced this world was filled with scoundrel outlaws.

"Hmm...perhaps I could provide some moral guidance to these wayward souls," thought Madara. But first, he needed to get his bearings.

"Oi! Who's the weirdo with the freaky eyes?!" shouted a young pirate wearing a straw hat.

Madara frowned. "You would do well to watch your tongue, boy."

"Shishishi! My name's Luffy! I'm gonna be King of the Pirates!" the boy responded. "What's your goal, weird guy?"

"Peace. A concept clearly foreign to savage lawbreakers like you," Madara scoffed.

Luffy just laughed again. "You're funny! Hey, join my crew! We could use someone strong like you!"

Madara raised an eyebrow, intrigued by this odd pirate's carefree attitude. Perhaps he would observe for now. There was much to learn about this strange new world.

Over time, Madara gained insight into the complex workings of this planet - from the mysterious Devil Fruits, to the tyrannical World Government, to the warring Yonko pirates who battled for supremacy.

After seeing Marines abuse their power, Madara realized justice in this world was non-existent. But he could change that by seizing control and instituting real order.

Observing the state of the world for some time, Madara turned his attention to Wano Country, which he learned was isolated from the rest of the planet. Intrigued, he covertly entered the closed borders of the island nation.

Madara was surprised to discover a massive battle underway between the Beast Pirates led by Emperor Kaido, who occupied Wano, and the alliance of Luffy, Law, Kid and the local samurai rebels trying to overthrow him.

He recalled Luffy mentioning his goal to take down Kaido and Big Mom here in order to become King of the Pirates. It seemed fate had led Madara directly into the pivotal conflict.

Seeing firsthand the tyranny and suffering inflicted on Wano's people by Kaido's ruthless rule, Madara was reminded of the corruption in his own shinobi world. He felt compelled to intervene.

The stage was set for a colossal war. Madara looked on as forces loyal to Emperors Kaido and Big Mom battled Luffy, Trafalgar Law, Eustass Kid and their ragtag fleet of rebel pirates and samurai forces.

"Let us test the might of these so-called Emperors," said Madara, leaping into action. The tide was about to turn...

Luffy cheered, "Go get 'em, weird-eye guy!"

On the battlefield, Madara casually evaded laser beams from Kaido's forces using his superior agility. "Child's play! Try harder!" he taunted.

"You dare mock Kaido?!" shouted King, who dove at Madara talons-first. But with his Rinnegan, Madara absorbed the ancient zoan's wildfire attack and redirected the flames back twice as strong, roasting King to a crisp!

"Gyaooo! He burned King instantly!" the Beast Pirates exclaimed in shock. But Madara had already disappeared.

"Looking for me?" Madara reappeared behind Big Mom and delivered a chakra-enhanced kick that sent the giant pirate queen crashing through three mountain peaks!

KA-BOOM!

"Impossible...he defeated Mama in one hit?!" cried Smoothie and Cracker. Before they could react, Madara trapped them in the Infinite Tsukuyomi and plunged them into happy dreamworlds.

Madara then confronted Kaido and flexed his Susanoo to life. "I am the only ruler this world needs!"

"Wara-ra-ra! Come you puny thing!" Kaido transformed into his massive eastern dragon form, blotting out the sun with his imposing size and let loose a devastating blast of lightning from his mouth. "Blast Breath!"

Boom!

"Child's play." Madara's armoured Susanoo formed rapid hand signs before slamming its palms into the ground. "Earth Style: Multiple Mud Wall Jutsu!"

Suddenly, immense rock walls emerged from the earth, shielding Madara from the lightning strikes. Then Susanoo hurled the stone slabs at Kaido, pummelling the dragon with colossal debris.

"Is that the limit of your power, Kaido?" Madara mocked.

Enraged, Kaido swung his tail with mountain-pulverizing force. But Susanoo caught the blow and the two titans struggled in a deadlock, the ground cracked apart beneath their feet from the outrageous power.

Kaido roared and shifted to hybrid form, his dragon claws was madly ripping gashes across Susanoo's armour. Madara winced but retaliated with a point-blank blast of scorching flames from Susanoo's mouth. The exchange of earth-shattering attacks continued, decimating the terrain for miles around.

BOOM! CRASH! KRAKOOOM!

Madara had yet to get serious. He manifested his Truth-Seeking Balls and hurled them at Kaido. As Kaido reeled, Madara shouted, "You're tamed, dragon!" Susanoo cocked back its fist before unleashing a catastrophic punch powered by the full might of Madara's chakra.

Kaido could only scream as the massive fist tore through his torso in a spray of blood. The arrogant Emperor had finally been dethroned!

"Guooooohh!" The forces of Wano stared in awe and terror.

Victorious, Madara ceased Susanoo and stared down impassively at Kaido's broken body. "Hmph. You were an unworthy opponent. My power exceeds all in this realm." Madara then turned to Luffy and said, "You will also submit to my authority or be destroyed!"

But Luffy boldly stepped forth with his fist raised. "No way! I'm still gonna be King of the Pirates, believe it!"

Madara tilted his head, bemused by Luffy's defiant spirit, so similar to Naruto's. Perhaps they were kindred souls after all...

Before Madara could respond to Luffy's defiant pledge, the air was suddenly filled with the crackling sounds of teleportation.

Fleet Admiral Akainu appeared along with the five Marine Admirals Fujitora, Ryokugyu, Kizaru, Aokiji, and Sengoku. They had warped to Wano to deal with the chaotic pirate situation.

"Straw Hat Luffy! It's time to join Ace!" hollered Akainu menacingly as magma dripped from his fists.

The Admirals unleashed a barrage of gravitation blades, blinding light beams, ice walls, and magma fists, decimating the landscape. But Luffy stood firm, ready to counterattack. Law and Kid prepared to back him up with their own powers.

Madara observed the Marines' overwhelming force. While chaotic, he recognized Luffy and his allies fought for freedom from the World Government's oppression. He was reminded of Hashirama's hopes for peace.

"Attacking those who only wish for liberty? Have you no shame?" Madara chided the Marines.

"Who is this stranger? He took down Kaido and Big Mom?" remarked Aokiji in surprise.

"It matters not! Eliminate them all immediately!" barked Akainu.

Madara stepped forward, ready to intervene against the Marines' abusive authority. "Hmph. Impudent fools. I will correct the corruption of your broken justice system here and now!"

"Meteor!" Akainu launched his deadly magma fists. But with Preta Path, Madara absorbed the attacks and retaliated using Almighty Push, sending the Fleet Admiral flying into orbit!

The remaining Admirals desperately unleashed their strongest attacks together, but Madara nullified them with ease using his Limbo clones.

"Is this all the mighty admirals can muster? Then you have already lost!" Madara mocked.

He caught all five Admirals in the Infinite Tsukuyomi, trapping their minds in a dream of new lives as farmers, shopkeepers, and anglers. Their tyranny was over.

With the Marines defeated, Nico Robin approached Madara. "Your knowledge of the Void Century could be useful to our cause," she noted.

Madara nodded. "Very well. I shall tell you of how the World Government came to power and suppressed the Great Kingdom." Perhaps they could be allies moving forward.

Later, as Luffy partied over their victory, Madara thought, "That fool reminds me of my past dream...a world where children could grow up happy and free."

He would test this unwavering spirit further by joining Luffy's quest to defeat the World Government and find the mysterious One Piece. If anyone could help him rediscover hope, it was this band of fanatical pirates!