All characters (c) Masashi Kishimoto.
The best thing about this fanfic is everything in it is canon so far.
Spoilers, as mentioned in the summary...
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She runs toward the body lying on the ground. She can't tell if it's dead or just unconscious. She can't even tell who it is.
When she reaches it and turns it over, she stares into the blank face of her raven-haired teammate.
"Nagato…" she whispers.
There is no response.
She shakes him, as if he is only sleeping and will awake at the slightest motion. She doesn't know what happened. She doesn't know what to do.
Then she sees someone approaching.
He is familiar.
He is…he was…her friend. She looks at him with new eyes now, filled with rage.
"Yahiko?! What have you done?" she screams. "Did you kill Nagato?" Standing up, still holding Nagato's body in her arms, she shakes with immeasurable anger. "What is going on?!"
She can't see the other boy's eyes. His head is bowed low, but she can tell it's not in shame or regret, or even pain. His spiked auburn hair and clenched fists are the same, but there is something about him that is different…something that is not…not quite…
"Answer me!" she commands, dropping Nagato's limp form. "Why did you do this? What has happened to you, Yahiko?"
She runs at him, prepared to strangle him with her bare hands, such is her fury, her shock, her pain.
Then he looks up and fixes her eyes with his.
And she stops cold.
They are not Yahiko's eyes.
They are Nagato's.
"What--?" she gasps, suddenly short of breath.
The boy across from her says nothing.
"What…what have you done?"
Silence reigns from his end.
"WHAT HAVE YOU DONE?"
She drops to her knees, wailing. She picks up Nagato's body, repulsed by the sight of it, but unable to let it go. She holds it to her, sobbing and screaming.
The thing that stands a few feet away, be it Yahiko or Nagato, steps toward her.
She stares at him, still crying. "You monster…YOU MONSTER!"
He does not stop walking toward her.
"K—keep away from me!"
He stops. "Konan."
She whimpers and clutches the body tighter.
"I am neither Yahiko nor Nagato. Not any more."
She does not notice the rain beginning to fall around her. She can only see Yahiko's reanimated body; she can only hear his voice and her own breathing, in and out, slowly, deeply…
"I am now, and will always be known as, Pein."
She stares at him, noticing for the first time the many piercings that decorate his face. They only add to her fear.
He advances a few more steps.
She sobs, softly, quietly, for herself, for Yahiko.
"No, Konan. Don't cry. There will be no more crying." He takes two more steps and closes the distance between them.
She looks at the ground, refusing to meet his ringed eyes.
His hand reaches out and tilts her chin up so she is looking at him, handling her gently, as if she were a porcelain doll.
He could not know he had already shattered her.
"I needed this, Konan. I needed this part of Yahiko. It was the only way to keep him safe, besides. I couldn't trust him with his own body. It wouldn't last much longer, the way he was."
"What are you talking about?" she breathes.
He sighs lightly. "You just can't understand. But no matter, you will. Together, you and I can rebuild this weak world into something strong, something beautiful—something to last forever."
She shakes her head.
"Don't say no. You're the only human being alive that I trust. My trust is valuable, Konan, and I advise you to keep it."
Her mind cannot take all of the thoughts it is being bombarded with. Her heart cannot take all of the emotions being forced onto it.
She feels like she is about to explode.
She sees him, she sees herself, as if she were standing a few feet away. She cannot stand how completely out of balance, how completely wrong everything is.
"Someday, Konan, I will become a god. And I want you to be my one, my only, angel."
There is no way out. There is no escape. Whatever his intentions, she has no choice but to go along with them, to play the part of the hapless doll over which he had complete control.
But she promises herself that someday, there will be a time when she will overpower him, destroy what he had created, destroy the monster that he had become.
She would allow the world to be what it had always been. She would allow people whom had known pain to cry. She would relieve whatever hurt he caused.
She would have her vengeance.
But for now, she would join him, quietly mourning, silently sobbing, as they played at gods and angels.