Do not question the timeline.
Prologue
Kakashi said things were going to be okay after he unceremoniously threw both her boys in opposite directions before they had a chance to plunge their equally fatal techniques through her ribs. From the dark look that passed Sasuke's eyes and bitter regret behind Naruto's, things definitely did not look okay. And to be honest, things were probably not going to be okay if she let Kakashi take care of it. He'd never been able to take care of anything except that orange book of his.
The wooden doors before her looked daunting but the prospect of losing her boys to each other was even worse. Sakura breathed a deep sigh and knocked firmly against the door.
"Come in!" The voice was booming.
She swung the door open, skipping the look Shikamaru threw her, who was donning a new Chuunin flak jacket that looked surprisingly good on him.
"I have a request, please!"
The smirk covered by Tsunade's hand sealed her fate.
She was three months into her studies when she had a gnawing, churning feeling in her stomach. Tsunade excused her hours ago but she was elbow deep in notes and asked to stay behind to finish reading about the coils of the chakra system.
Darkness wrapped itself around the village and fifteen minutes later, her desk was empty. Thirty minutes later, her heart was empty with nothing but two words.
Thank you
She hated those words.
Naruto was wrapped up to the nose in bandages and still managed to smile brilliantly at her after being stunned by her presence. She could tell from the partially undone layers that he tried loosening them several times. She smiled softly at him, cupping his cheeks fondly and so out of character that it stopped him dead in his explanation.
"I'm sorry." She said and then stood up as Naruto turned wide eyes towards her.
He was stammering out promises and Shikamaru was frowning at her from his position in the corner of the room. "I'll get him back, I promise, Sakura-chan."
Kakashi promised things were going to be okay. They were not. Naruto promised to bring back Sasuke and she wasn't sure that was a promise she wanted him to carry.
Shikamaru pushed himself away from the wall, frown dipping even lower than Sakura thought possible.
"Sakura, he's trying to-"
She stopped in front of the sliding door and cut a sharp look to Naruto. So sharp that Shikamaru forgot what he was trying to tell her in defense of his friend.
"Did Sasuke-kun do that to you?" She asked softly.
She was met with silence and it was enough for her heart to break.
Naruto left and Sakura studied.
She studied hard. She learned about the human body until she dreamed about the red and blue veins of anatomy. She studied the physiology and psyche of the human. She studied kekkei genkais, extinct and current bloodlines. She studied the old clans of Konoha and the realities of war. She immersed herself in the foundation of not just her village but the advent of Shinobi. She memorized years of diplomatic treaties, allegiances and enemies of the nations and most of all she studied herself.
Sakura soaked her hands and feet with knowledge for two years, traveling to different villages, taking odd jobs and small pay for the gain of wisdom. She helped old shopkeepers on the outskirts of villages where kunai punctures marked their walls and names like Hoshigaki Kisame and Uchiha Itachi did not paralyze them. She realized the best way to obtain information was not inside the walls of her village where information was partial to loyalty.
And then she understood why being objective was cohesive to being a shinobi.
Sakura was on the brink of figuring out how to transmute mutated cells into regenerative cells when she felt it. An unknown and dangerous presence in the studies of the Hokage's personal library. A personal library no one but three authorized figures had access to. She being one of them and the person in the room with her not being the other two.
The cloaked person drew closer and she went still, her breath leaving her the instant her eyes met red.
Knowledge was truly a powerful thing. Sakura learned, though, that it came with a deadly price.