I'm taking real liberties about the landscape. Warnings for depth.
The Path of Brotherhood
If it had been Sand or Grass, perhaps Sasuke would have felt differently about leaving. Or perhaps his feelings would have just been more obvious. Not that he had any on the subject -- getting out of Fire country as a missing-nin was just something he had to do. Just like living in this new place as a Sound ninja.
It was Orochimaru that suggested that he take walks and spend some time alone. Sasuke wasn't sure what to make of that, but he did admit, privately, that his focus was much better after them. He felt refreshed; as if there was something "out there" that replenished him, offsetting what Itachi and Orochimaru would take from him. What he would take out of himself.
However, it wasn't always like that. Some days, the light through the trees would hint at something like a sunrise of days of free time and it would be all Sasuke could do not to not rip his opponent's throat out on the next sparring match. On those days, Sasuke kept to locking himself in a the dampest, darkest corner of sound and setting enough boobytraps around the area that Kabuto would be the only one willing to fetch him in the morning.
Sound wasn't really what he expected when he left Fire country. They told each other jokes, played games, slacked off on guard duty (everyone thought it was funny at how upset Sasuke had been about this), and overall, acted like regular human beings. Sure, if you did certain things you would be killed immediately (directly serving under Orochimaru was a great honor and an equally great risk), but Sasuke didn't really have to worry about that. No matter how upset or provoked Orochimaru was, he never took it out on Sasuke.
And so Sasuke would make himself scarce whenever Orochimaru was angry.
There were days that he hated the Sound. It always reminded him of his past, what he left, where he had gone... and who was still alive. It wasn't like a gloom like the shrine he kept at his clan's complex did, but nevertheless it /lived/ through him. And he blamed Sound for it.
If Sound didn't have trees, then maybe he wouldn't be find himself walking up and down them all the time. If Sound didn't have water, he wouldn't have to see his reflection or the fish swimming below them. If Sound didn't have such lazy people performing guard duty, then he wouldn't have to hear their chatter while he slept facing away from the fire...
Sasuke decided that he needed a war.
Or maybe he just needed someone to argue with and beat up. But he had tried that at sparring practice (the beating up part) and was then told in no uncertain terms that a no-holds-barred fight was off-limits to someone too important to kill like Sasuke, and that if he tried to kill someone, they would find ways to restrain him.
Sasuke tried it once. He didn't try it again. Not that he ever /got/ to the point that he had to try it again, but that wasn't exactly the point. Having his chakra locked and forced to dress and work as a girl in the kitchens had been more than enough humiliation for him to take. That and... He almost attempted murder again and it was only when Orochimaru stepped in did Sasuke look into his mentor's eyes and finally saw.
He had activated his Sharingan without even knowing. He thought he had outgrown that a long time ago.
It was after that that Kabuto personally became in charge of monitoring Sasuke.
He was refused his request to be sent on missions that Anbu in Leaf would normally be given. It was only after several straight weeks of bargaining did he manage to get himself on a team... and even then he could tell from the looks of his new teammates that they would treat him like a child. A deadly child, but still a child.
They stopped treating him that way when he kept one of them from being hit with the Rasengan and several other things in the chaos when they were ambushed on their second mission. Before Orochimaru could say anything, Sasuke personally refused to go on any missions for the rest of the month. Naruto was alive. How, he didn't know, but he was alive. Now the guards that would previously try to goad him into playing a game of cards now silently/guiltily watched him as he faced away from the fire.
His training became more and more harsh as pressure from Orochimaru increased. Sasuke preferred it that way, but he also hated the looks he got for it. They were afraid of him. "They" did not, but "they" treated him with respect. He was allowed to go on a few missions. "They" also taught him things along the way. Sasuke learned more and more and improved by leaps and bounds. It was everything that he came to Sound for and he was getting it now. His goals, his hatred, his everything was coming closer to his grasp.
Then, one day, he threw an attack he rarely used and heard his opponent behind him, too late, too soon.
"What are you looking at? I'm right here you--"
His opponent never got to finish as everything went red. Suddenly, everything he had worked so hard for, everything he had built, simply collapsed. By the time he roused himself from his panic, Sasuke found himself just on the border of Sound, holding his right arm as it spasmed from strain from using the Chidori. He shivered. It was beginning to rain and he had nowhere to go.
It wasn't as if he couldn't go back. Orochimaru and Kabuto would let it go without even a shrug of their shoulders. Kabuto had hinted often enough what Sasuke was under supervision for. And as much as it made Sasuke want to kill someone, he had to admit that killing someone just because they reminded him of Naruto or Kakashi was stupid.
Sasuke wasn't stupid.
He could go forward, too, but where would that be? Maybe he could go to Grass, he thought suddenly. Maybe there would be something different for him there, and maybe his life would stop being so cursed and haunted by living spirits. Maybe he could find his br--Itachi and they could all be dead finally...
He ran.
It wasn't until almost a year later, when Naruto found him in the most deserted part of Earth country did his yelling of, "but do you HAVE to live Itachi's life instead of your own?.!" did he find himself stop suddenly in his tracks.
And it was his reply that began everything.
"No, you idiot -- I've been living both."
