Disclaimer: Naruto is not mine.
If the long hours that Sakura put in each night studying the various textbooks, charts, scrolls and journals that she had borrowed from the Hokage's personal library had taught her anything, it was that the human body was a complex and beautiful structure. Every bone, ligament and organ had a distinct purpose that only it could fulfill.
It was in that way that the human body reminded her of Konoha. Every villager had his or her role to preform for the village to function as smoothly as possible. Tsunade was Hokage and as such she was responsible for the safety of the villagers and overseeing everything in the village. She made decisions based on what she thought would keep the villagers safe and out of harm's way. Sakura was the Hokage's pupil and as such it was her duty to study as hard. It was her responsibility to learn everything she could about healing in the hopes that the knowledge would assist her when it came to practical application of the skills Tsunade was teaching her.
That was why Sakura found herself awake at four in the morning, ignoring the monotonous ticking of the clock and the way her eyes ached and watered from reading for hours on end without reprieve. She ignored the soft mattress on her bed beckoning sweetly and readjusted herself on the hard chair before her desk. Determine to press forward, Sakura flipped the page of the textbook she was currently reading.
With a single finger, she outlined the diagrams on the opposite page from the column of text she had just finished reading. The diagrams were composed of two pictures of the same generic, faceless woman. Both of their bodies were spliced down the middle, exposing two different views. The one on the left was a diagram of the nervous system, while the one on the right was of the circulatory system.
As her finger traced the dark ink of the bodies' outlines, Sakura found herself repeating the names of the organs and their purposes in her head like a mantra: the nervous system contains the brain, spinal cord, peripheral nerves, it controls behavior, movement, physiological processes, it uses electrical signals; the circulatory system contains the heart, blood vessels, blood, it transports nutrients, gases, hormones and waste within body. When she got to the end, she started to repeat it to herself--the nervous system contains the brain, spinal cord, peripheral--when something popped into her head that caused her to frown.
The section of the textbook she was reading was just a review of basic information that healer nin were suppose to memorize within the first month of their training, but as Sakura repeated it to herself, she found herself faltering. She knew their names and their biological purposes--that was the easy part, after all--but she suddenly realized that she didn't know anything about the organs in her own body.
Was it a defect in her heart that was responsible for the fluttery feeling she felt in her chest every time that Tsunade leaned over her shoulder when she was explaining a detailed problem, or was that a misfiring neuron in her brain? Was the shiver that ran through her body when she smelled sake an allergic reaction, or was it simply a response that had been conditioned into her to recognize Tsunade's presence? Sakura found herself unable to answer her own questions.
She knew that there must be a medical or psychological explanation for them somehow, if only because the alternative--that the flutter in her chest or the shiver running through her body were the beginning signs of a crush--was too ridiculous to contemplate. The reason that she had sought out Tsunade as a tutor in the first place was because she was the best healing nin in the village and, more than anything else, Sakura wanted to grow stronger so she could help Naruto bring Sasuke back. The thought that she would fall for her teacher when she was already in love with Sasuke was beyond crazy; it was impossible.
Or was it? Sakura's headache had become so severe that she couldn't think clearly anymore.
She laid her head down on her desk, telling herself that she would only rest her eyes for ten seconds, but the moment her eyelids slipped closed, she quickly fell asleep to dreams of blond hair and brown eyes and warm skin beneath her searching fingers.
In the morning, Sakura would oversleep and be running late to her morning lesson with Tsunade. By the time she would wash her face, find a clean dress to wear, compose herself in front of her dressing mirror and realize to her devastation that the spine of the textbook she had been using as a pillow had left an imprint in her cheek, the last fragile remnants of the dream she had had would be lost--if only until she caught Tsunade's scent again and tried unsuccessfully to reason away the blush on her cheeks as her body's attempt to regulate her body temperature.
Sakura didn't know it yet, but it was only a matter of time before she realized that her heart served two masters, neither of whom would ever return her feelings, but both of whom she would love with unerring loyalty for the rest of her life.