After a day of running through the mountains, Itachi had finally picked-up a trail left by Sakura. It was about 3 days old and was fading away fast, but he had found it nonetheless. Thanks to his Sharingan, Itachi had followed her chakra signature down South before heading full East once again, and over the borders of Sound. He wasn't exactly thrilled by the idea of stepping into a hostile Country with no back-up, but then again, one lone ninja was always harder to spot than an entire platoon.
The oldest Uchiha heir had always been very good at hiding his presence; ability that he had perfected during his first year in ANBU. After all, being able to erase completely your presence during a recon or infiltration mission usually made a big difference in life and death situations. He had quickly honed the skill, and also used it around Konoha in order to keep tabs on his little brother.
After Naruto had came back from his training with Jiraiya, the members of Team 7 had passed the Jonin exam with flying colors. Even if Sasuke and Sakura could have obtained the rank of Jonin the year before, the two had decided to wait for Naruto to come back before passing the exam together. But once that had accomplished that, the noisy blond had wanted to join ANBU, much to Itachi's displeasure. Personally, he didn't mind if the young Uzumaki wanted to join ANBU, and actually thought that it would teach the ever so energetic ninja a thing or two about discipline. Unfortunately, what bothered him was the fact that if Naruto asked to pass the ANBU test, so would Sasuke.
Of course, Itachi was very proud of his Otouto, and knew that Sasuke had the skills and levelheaded personality to pass the ANBU qualification exam. But Itachi, having been an ANBU Captain since the age of 13, had seen a lot of things that he hoped his little brother would never have to experience.
That's when Itachi had begun to take shorter missions in order to keep a closer eye on his brother. He had even asked the Hokage to give them longer A or S ranked missions in order to keep them out of Konoha during the yearly ANBU exams. This ruse lasted for three years before Sasuke started dating Naruto's cousin Karin, a very talented medic-nin, and decided to take up a job as a teacher at the Academy.
Itachi still remembered the night his Otouto had announced his attentions to their father. Fugaku had been enraged that his youngest son didn't want to join the special elite forces like Itachi had, but Sasuke had proudly held his head high like any other Uchiha, and defended his own choices. It was probably the first time Sasuke had stood up against their father, instead of taking the scolding in silence like he usually did. A few days later, Team 7 left for Suna, the hidden village of Sand, so that Naruto could ask the Kazekage Garaa if he was willing to help the energetic blond train in order to become Konoha's next Kage. Thankfully, after that no members of Team 7 had asked to partake in an ANBU exam, much to Itachi's relief.
So yes, the eldest Uchiha heir had kept tabs on his little brother, and thus the rest of Team 7, but what he hadn't expected was that he had been taking more and more tabs on Sakura, and less tabs on his little brother. At first, he hadn't even realized that he was following Sakura more often than not. It was about one year after Naruto had came back that his little brother had called him out on it. Of course, Itachi had shrugged it off as mere curiosity, which wasn't an entirely false pretense. He was truly impressed by how the single daughter of a civilian family had raised herself to become as talented as the legendary Slug Princess. He was curious about her. She was vibrant and lively around her teammates and friends, yet deadly and serious in a fight or on the field.
So even if his cloaking technics were remarkable, it was a slip-up that had allowed this simple curiosity for her to morph into plain fascination.
It had happened about three years ago, when Itachi had been heading back home from a mission when, from the rooftops, he had spotted her. She was actually very easy to find, with her ridiculously bright hair. It was a wonder how she hadn't gotten herself killed yet.
That day, she had clearly been in a sour mood, stomping her way through the streets, glaring at anyone who didn't move out of her way fast enough. His curiosity had gotten the best of him as he carelessly followed her into an alley. It was only once he had been out of sight and deep into the alley that she had cornered him and called him out on his stalking. Apparently his Otouto had let slip that Itachi had taken a habit to keeping tabs on Team 7, and in her annoyed state she had given him an earful on how Sasuke was big enough to take care of his own business and did not need to be babied by him. He had stayed silent, wondering when he had messed up and she had detected his presence, but Sakura had taken his silence for something else. Fury had been clear on her features when she had asked him if it had been Sasuke that had asked him to keep an eye on her. She had then started scolding him like a little child, saying that she was old enough to decide WHO she dated, and that it was no one else's business, other than her own.
When he had only stared at her after her rant, not sure if he had understood the context of her previous speech, Itachi had probably raised a single eyebrow her way. It was a tick he rarely noticed he did, but he knew that it drove his little brother crazy, so had never bothered with learning how to control the slight twitch. At that, she had only turned around and stomped off, clearly exasperated.
That night, during diner time at the Uchiha's main household, his little brother had arrived at the table covered in bruises. After a few minutes of probing from a worried Mikoto, Itachi had discovered that earlier that day Naruto and Sasuke had ruined her date with another Jonin that was, from their point of view, 'not good enough for their Sakura'. That day, Itachi learned 2 things about the pink haired medic: 1 - that she had broken her record in 'how far can I punch Naruto?'; and 2 - that Sakura's temper was probably more devastating than the Godaime Hokage's.
But that only made her that much more interesting to him.