Thud. Thud. Thud.
The monotonous hammering continued, as Sasuke Uchiha frowned in deep concentration.
Thud. Thud.
A voice was heard calling from the outside.
"Sasuke! You have to stop this!" A woman's voice screamed.
The last Uchiha grit his teeth. That was probably Sakura.
"This is the way it should be." He called firmly. His black hair swirled as he turned his head to face the door.
"You don't mean that Sasuke! Please, just come back out! We can talk things ove-"
"No."
He spoke with finality, and after forming a single handseal, there was silence in the room.
With that, Sasuke turned back to what he had been working on.
Stretched over a massive stone table, the only one in the small stone room, were dozens of scrolls laid open. On the sides, numerous scribbles could be seen. These were the notes of an obsessed man looking for a solution.
Behind him, he heard a soft slithering sound.
"Ku ku, to think you were working on something as complicated as this." The snake sannin grinned amusedly. "I can't say I'm surprised. You always were a stubborn one."
Sasuke clenched his fist, but said nothing.
"Will it work?" He asked curiously. "I assure you, I have studied the subject quite thoroughly, and so far as I know-"
"It'll work."
Orochimaru grinned at that. "I look forward to seeing it then."
Sasuke bent up from the table, and walked over to the wooden coffin lying against the wall. It had been hand-crafted by Hashirama those ten years ago, before the old Hokage had returned to the afterlife.
It was nothing less than his friend deserved.
Outside, an earth-shattering quake shook the room, sending dust falling from the ceiling. It pounded again and again, and behind him, Sasuke could see the wooden door cracking ever so slowly.
It figured that even the strongest seals in the world wouldn't keep Sakura out for long.
Sasuke, the Sixth Hokage of the Hidden Leaf, turned away from the door for the last time. He collected himself, and then with purpose strode up to the wooden coffin.
He slipped easily into the firm wood. He was a little too tall for the it, but the man couldn't care less.
It wasn't meant for him.
As the Snake Sannin watched with interest, Sasuke flashed through handseal after handseal. The pattern seemed endless, weaving and pulling Chakra in complex ways.
Then, with a final handseal, he slid to the back of the coffin, sighing in exhaustion.
As his body started glowing with inner light, he turned to the old snake, wearing the first smile he'd had in nearly ten years.
"The Impure Resurrection was always flawed." He said to Orochimaru. "But they never understood why."
Sasuke shuddered, before continuing. "There was no sacrifice. They only offered a corpse, and so the result was impure."
He looked the Sannin in the eye.
"Only a life can pay for a life."
The snake grinned widely, his teeth reflecting the light.
"How interesting."
Sasuke continued to glow brighter and brighter, until even the enhanced eyes of the old Sannin couldn't take it, and he turned away covering them.
Inside the glow, Sasuke Uchiha, last bearer of the Sharingan, closed his eyes.
"This is where it ends." He muttered, before the light exploded out in a wave of energy. It shook the cavern, and blasted the wooden door off its hinges. The Snake Sannin was thrown against the wall, mostly unharmed.
When the body's eyes opened again, to the stunned face of Sakura Haruno, the face smiled warmly.
They were a deep, cerulean blue.