Harry Potter: Toji Potter

Black Zetsu slithered through the battlefield unseen, a shadow within the chaos, a whisper lost in the cries of war. The so-called "Great Ninja Alliance" was too focused on their battles to realize that their greatest enemy had never been Madara or Obito.

It had always been him.

Madara had believed himself the mastermind. Obito had thought himself the savior. Even the shinobi believed they were fighting for their future. But Black Zetsu knew the truth—they were all just pieces in a game older than this world itself.

A game he had already won.

The First Step: The Sealing Jar in Kumo

Black Zetsu slithered toward a forgotten corner of the battlefield, where an unguarded relic from the Land of Lightning remained.

The Kohaku no Jōhei—The Amber Purifying Pot.

It had been used to seal the Eight-Tails once. But more importantly, it still contained traces of its chakra from long ago.

A single strand of tailed beast chakra—that was all he needed.

As his form melted into the pot's surface, tendrils of black ooze slithered within, siphoning the remnants of Gyūki's chakra. It was barely anything, but it was enough.

A malicious grin spread across his twisted form.

The Second Step: Reawakening the Ten-Tails

Now that he had what he needed, the next step was simple: reconstruct the Ten-Tails.

He merged into the ground, swiftly moving toward the site of battle. The Tailed Beasts—Harry's shield had repelled them, but that did not matter. They had already left behind fragments of their chakra in the very earth they stood upon.

Black Zetsu seeped into the terrain, absorbing these traces like a parasite drinking from its host.

Shukaku's grains of gold-laced sand.Matatabi's scorched embers.Isobu's drifting mist.Son Gokū's lingering fire.Kokuō's faint steam.Saiken's dissolved slime.Chōmei's errant scales.

It wasn't perfect, but it didn't need to be.

It only had to be enough to force the Ten-Tails into existence once more.

The Third Step: Reviving Madara Uchiha

Black Zetsu's voice slithered through Obito's mind like a venomous whisper.

"Do you see it now, Obito? The Kage have failed. Harry Potter is stronger than we expected. But Madara… he is still the key."

Obito's single Rinnegan pulsed. He clenched his jaw, sweat dripping from his brow.

"I…" His breath was ragged. "I don't need Madara fully revived yet. I can still—"

"No… you cannot. You are failing."

Zetsu twisted, coiling around Obito's body like a black serpent.

"Do you want to lose to that brat? To let Naruto Uzumaki, the child you underestimated, surpass you? To let Harry Potter crush your dreams?"

Obito's fingers twitched.

"Do it."

Obito's hands formed the Rinne Tensei seals.

The jutsu of resurrection.

The technique that would bring back Madara Uchiha in his true, living form.

The Fourth Step: The Absorption of the God Tree

Madara's eyes fluttered open.

He was alive. Truly alive.

His fingers flexed, his lungs filled with air, his body surged with newfound strength. And yet… something was missing.

The Ten-Tails.

The God Tree.

Black Zetsu slithered forward, his voice dripping with reverence.

"You are incomplete, Lord Madara. But I will guide you."

Madara turned, his Rinnegan scanning the battlefield. His lips curled into a smirk.

"Then let us begin."

He stepped forward, hands raised, calling upon the Chakra Fruit's power.

The God Tree's roots burst from the ground, twisting and wrapping around his body like a cocoon.

Madara did not resist.

He embraced it.

His body absorbed the chakra of the Shinju, his form growing stronger, more perfect.

He could feel it—limitless power surging within him.

And then…

Something changed.

The Final Step: Kaguya's Return

Madara's triumphant smirk faltered.

He felt… wrong.

Something cold slithered up his spine. A darkness clawing at the edges of his soul.

"Yes… it is time."

Black Zetsu pierced into Madara's back.

The great Uchiha's body stiffened. His hands trembled. His Rinnegan widened in horror.

"You—!"

"You were never in control, Madara. You never were."

Black Zetsu's form crawled up his skin, wrapping around his body.

"This was never your story."

Madara's body convulsed. His chakra—his soul—his very existence—was being rewritten.

As his form twisted and morphed, a new presence emerged from the darkness.

A figure of pale skin and celestial grace.

A woman with horns and flowing robes.

The Rabbit Goddess had returned.

Kaguya Otsutsuki opened her eyes.

And the world trembled before its true master.