Disclaimer: Never going to own Naruto.
It's possible to forget emotions.
It's like speaking another language.
If you don't speak it
or see anything related to it for a long time,
you slowly forget it.
So it's possible.
It's possible to forget how to smile.
The little boy scampered home after a long day of playing out in the fields by his village. He opened the front door to his home, where his parents were waiting.
"Mom! Dad! I'm— "
His mother grabbed his arm and pulled him into the house. She flicked all the lights off.
"Mom? What's—"
She clamped her hand over his mouth, shaking her head frantically. They crouched down in a corner. But his father remained standing in front of the door.
The little boy was about to say something else, then he realized. There was someone outside. By the feel of his chakra, he was a threat. He knew what was going to happen before it did.
His father opened the door.
There was a man standing in front of the house.
The man might have once have been handsome, but age had withered his features. He might have once stood tall, but time had stooped his backbone. His right eye was covered by a bandage.
"Danzo . . . the Shinobi of Darkness."
The man nodded. "Still sharp as always. You should know why I'm here."
"It doesn't matter. I'm not going down without a fight," snapped the boy's father.
He assumed a battle stance, as did Danzo.
The fight was short and violent. Within fifteen seconds, Danzo had him pinned to the ground with a kunai to the neck.
"How your reflexes have dulled . . . what a pity. Why did you leave the Foundation? You were one of the most gifted ones . . . I'm sure your son will be too."
The last thing that the little boy's father saw was a red eye peeking out of the bandages.
Footsteps, footsteps approaching the house.
"Run!" hissed the little boy's mother. The little boy refused to move.
"No, Mom, I'm my dad's son. And I'll—"
The door opened, and light streamed on their faces. Danzo spoke.
"He's coming with me."
The mother held the boy a little closer.
Danzo strode forward. "Now. Or you die. Either way, he's coming with me."
The mother was torn for a moment. Then she looked into the little boy's eyes for one last time.
"I want you to be happy, Sai. Smile for me one last time."
The little boy smiled, bright and sincere. To his mother, his smile was the most treasured thing in her life.
"Good." The mother hugged the boy. "Remember me, remember your father. Remember your name, but most of all, remember your smile."
Then she was gone.
Danzo walked forward and held out his hand.
"Come, little boy. Join me, as your father once did."
The little boy walked forward and took his hand.
"Good." Danzo smiled, and leaned forward, exposing his Sharingan eye. "Your name is Sai. You are now one of the Foundation."
The little boy smiled, but it was not the same as before. "I am a Sai, a weapon. I will be your weapon, I will obey your orders, I will serve you until I die."
Ten years later, Sai looked into the mirror.
"Smile," Danzo said.
Sai tried to smile.
"Again."
He tried again. His mouth came out as a grimace, twisted and malformed.
Why can't I smile?
Danzo walked away.
Sai tried and failed again.
Why?
When we are young,
smiling is a feeling,
an emotion.
When we grow older,
smiling is no more
than a mere facial expression.
