Disclaimer: Naruto belongs to its proper owners; ie. not me.
Friends
Sasuke had determined early on that he has no need for friends. Much like fostering attachments to earthly possessions – like family, his mind whispers malevolently– friendships only invite unnecessary emotions and distract him from his ultimate mission.
Despite many statements to the contrary, he is not friends with the other members of Team Seven. He only tolerates them in order to clear his missions and progress further along ninja ranks, thus coming closer to his goal. Whatever outing he has been dragged to by Sakura and the half-wit blonde is merely out of obligation. Logically, there is no fun to be derived from spying on Kakashi to unravel the mystery behind his face cloth, or from fishing trips to the river that snaked through Konoha. And if he enjoys himself on such outings, he is careful to shut that metal-enforced door before his mind can process the information.
Friends, he thinks, are useless.
Friends are the people who understand you the most. The ones that have seen your ugly sides as well as the pleasant and still stick around to put up with the occasional bout of pigheadedness. Friends are there to talk to, to hang out with, and when the need arises, pound some sense into you. Friends forgive the stupid and inconsiderate things you've done and, despite you being a complete bastard, still give chase when you betray your comrades and turn your back on the only place you've called home.
When everything is over and you have made an enemy out of everyone, friends welcome you by beating you within an inch of your life, but without any questions.
But Sasuke has no need for friends, and if a picture of a blue-eyed blonde whose incorrigible tenacity almost rivals his stupidity comes to mind, he does not dwell on it.
His body broken and held together by will alone, his hands stained with blood from where they had pierced flesh, Sasuke turns his back to the blonde crumbled on the ground.
"I'm sorry, Naruto," he murmurs and wonders for a moment whether the tenderness in his voice is truly his own.
And so, he leaves The Valley of the End, his home, the only life he'd known, and the only person that dared to reach the status of "friend" behind. Sasuke does not need friends; he is an Avenger, he is alone.
End.