Sasuke's letter to Kakashi after he left Konoha
"Now that I've left, I will have to inform you that there are still things I need to tell you. We were short on time, so I could not say everything I intentended to you. That's why this letter will serve the purpose.
First and foremost Kakashi, you seem to believe the last fight between me and Naruto caused me to forget about my grude against Konoha. No matter how nice that would be, it is clearly not the case. Now I know you have never made an effort at understanding my circumstances but you should keep in mind that I do not intend to return ever. If Naruto ever tries to chase after me again, hold him back. I believe you can keep him busy if you place him into the Hokage position some time in the future. Konoha has not changed, it never will. My intention was to change it and lead it but for that to happen I had to kill Naruto. It's something I could not do. Especially not after the words of him that moved me so. He's a precious friend - one of the few who understand me, yet he is still an idiot.
Secondly Kakashi, you were quite prone to forcing Sakura onto me. Here is something you need to know. I won't deny the simple fact that I have /always/ hated Sakura with a passion. From the day she insulted Naruto for being an orphan I hated her. I seriously wanted to kill her on several occasions. Unlike with Naruto, there was never anything at all that would have held me back from killing her. I don't love her, and she will have to move on accepting that- I do honestly not know how much clearer I can make myself. I see a strong connection building up between her and Naruto. As a former teacher and now father of the village I suggest you encourage that connection. We both know how much Naruto liked Sakura from the day we entered the academy. Sakura's love for me is an illussion. Deep down she loves Naruto, he's the man who always saved her. He was by her side while I was occupied elsewhere. I barely wasted a thought on Sakura. My entire thoughts were filled by Itachi and my clan. Sakura doesn't know me, thus her love is nothing more than an illussion. I won't deny what I already told Naruto. Team 7 made me remember my family. But it wasn't the people. It was the strong bond we developed. However, Team 7 was never able to replace my family. I was clinging desperately onto something that would save me from my loneliness. Until I realized what was truly important in my life I relied on Team 7 for that.
Though there was only one person of Team 7 who completely understood me. Naruto. I found a new team. A new replacement for a family and I decided to once more walk my path alongside them. I have deliberately chosen to stay with them because they are the people who understand me best. We share the same bridge of loneliness and sorrow that haunted us throughout our entire lives.
I will make sometime to come and visit perhaps, one day. Although Konoha holds many ill memories I do not wish to remember. Send my greetings to Naruto and Sakura. I am aware everyone else in the village detests me so there is no need to send them my regards. Meanwhile, I will be starting a new life. You will hear of me soon enough, Kakashi."