The Secret of the Mangekyō Sharingan
"Itachi—your path was wrong."
The moment Sasuke said it aloud, a violent surge of emotion rose in his chest.
For the first time, he wasn't the child being led by the hand.
From the night of the massacre onward, everything had been decided for him. His survival. His hatred. His future. Itachi had never asked what Sasuke wanted. He had never offered a choice—only outcomes.
Being trapped inside someone else's plan felt suffocating.
Now, standing here, Sasuke was finally rejecting that path with one of his own making.
It felt like stepping out of a cage he hadn't even realized was locked.
"Hmph. Still as arrogant as ever," Itachi replied coolly, the corner of his mouth lifting. "Very well. I'll remember those words."
"You won't just remember that," Sasuke said, staring him down. "I'll defeat you completely. Use it, Itachi. Your proudest illusion. Try killing me with your Mangekyō."
Itachi exhaled softly and rose from the stone throne.
"You're confident. But do you truly understand the Mangekyō Sharingan?"
"Whether I understand it or not doesn't change the outcome," Sasuke replied.
He wasn't wrong.
Even the clan stone tablets had been vague. They recorded how to awaken the Mangekyō—but nothing about what came after.
"The Mangekyō is a cursed evolution," Itachi said calmly. "From the moment it awakens, it begins walking toward darkness. The more you use it, the closer it comes to being sealed."
"…What?" Sasuke asked, unhurried.
"One day, it goes blind."
"So that's the price for controlling the Nine-Tails?" Sasuke frowned slightly. He had only just awakened his Mangekyō. He hadn't felt any decline yet.
If he'd had time to speak with Kakashi, he might have learned this earlier—but time hadn't allowed it.
"Otōto," Itachi said quietly, "your understanding is shallow. And this is only the surface. There's another secret to the Mangekyō—the most important one."
He stepped closer, stopping just outside a distance both of them instinctively recognized as dangerous.
Itachi squinted, as if trying to read a distant blackboard without glasses. Sasuke's form was already blurring.
So it's gotten this bad, he thought.
Closer still would mean triggering the true battle. Too early. Not yet.
Sasuke waited in silence.
If Itachi had brought this up, he intended to explain it fully.
And Sasuke understood why.
He's trying to give me everything he knows.
The realization left his emotions tangled.
Itachi studied him, faintly surprised.
The Sasuke he remembered would have pressed for answers immediately. This one didn't rush. He observed. He waited.
Not just stronger—but steadier.
"That's good," Itachi thought. "This is better."
Aloud, he said, "Then let me tell you some history. The part the clan buried."
The surroundings shifted again. Sasuke knew it was still an illusion—but one rendered with unsettling clarity.
And then Itachi spoke.
Madara Uchiha, one of Konoha's founders, had once had a younger brother. From childhood, the two competed relentlessly, sharpening each other through rivalry.
Both awakened the Sharingan.
Seeking greater ocular power, both sacrificed those dear to them—and both awakened the Mangekyō. The first in Uchiha history.
With that power, they unified the clan. Madara became its leader.
But overuse came at a cost.
Madara's vision faded. Slowly. Inevitably.
He tried everything. Nothing worked.
Desperate, he made a choice.
He took his brother's Mangekyō and transplanted it into himself.
Light returned.
And this time, it never faded.
Thus was born the Eternal Mangekyō Sharingan—along with new, unprecedented ocular abilities.
But the process was flawed. It only worked between siblings. And even then, not always. Countless died trying to replicate it.
The truth was simple and cruel:
Only two brothers who both possessed the Mangekyō—and one who claimed the other's eyes—could produce the Eternal Mangekyō.
That was the Mangekyō's greatest secret.
Itachi didn't stop there.
"Madara survived his final battle," he continued. "He lives on—his power intact. He founded Akatsuki from the shadows. Sixteen years ago, the Nine-Tails attack was his doing."
"But he lost," Itachi said, voice sharpening. "Stopped by the Fourth Hokage."
"Madara stands at the peak of the Uchiha no longer."
His eyes burned as he raised his hands, fixation locking onto Sasuke's gaze.
"With your eyes, I can awaken the Eternal Mangekyō."
"I will surpass Madara."
"I will approach true revolution."
His expression twisted, fervor spilling out.
"Sasuke!"
"You are my new light."
"My spare eyes!"
Behind him, an enormous, grotesque shadow formed—an illusion of a monstrous being with Sharingan eyes, tendrils reaching for Sasuke.
The vision pressed in.
"The Uchiha are a clan that murders comrades for power," Itachi ranted. "That kills kin for eternity. A blood-soaked lineage that worships this curse!"
"And you were born into it!"
His body trembled, Mangekyō blazing.
"Come! Let me kill you and free myself from this destiny! We are each other's spare eyes—this is the bond between brothers!"
Throughout it all, Sasuke remained silent.
Then he opened his eyes.
The phantom tendrils shattered instantly.
Reality snapped back.
Itachi stood exactly where he had been all along—expression controlled, body unmoving.
Sasuke met his gaze calmly.
And said,
"Itachi… no one ever told you your acting is terrible?"
...
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