It is a strange feeling, to be hated by those you hold dear, by those you have sworn to protect and obey. But only four people knew the truth, so it was acceptable for the others to hate me. The others would never know the truth and that was the way I wanted it. I didn't want them to know that I had slaughtered my own family because I was ordered to.
Shinobi are naturally suspicious. We have to be to survive. And most of the time, that suspicion is unjustified. And usually, that suspicion is proven to be wrong. I don't think that they ever realized it was wrong. We Uchiha disliked the villagers and its leaders for their distrust, even made plans to rebel, but we would never have wished for their deaths. Never wished for the death of the Yondaime. But that is what they believed and there was nothing we could do.
When the time came that their paranoia told them we were bent on their destruction, they ordered me, their little tool, to kill my clan. And I did because I always followed orders. I would never follow blindly again.
I killed my mother, my father. I killed my friends and their mothers and fathers. I killed cousins, uncles, aunts, teachers, and their friends and family as well. But I could not, would not, kill my baby brother. He was too young, too innocent. He was the youngest of the clan at that time and he deserved so much more. He deserved to realize his potential. He needed to avenge our clan, but take that revenge on me for it was I who followed those orders.
There are two things in this world that make us strong: love and hatred. I knew the instant I set my blade against my clan that he would never love me again. And so I would be sure that he hated me, hated me with all that he was so that he would live and be strong and take revenge and one day be my end. I had not the courage to take my own life and I have always regretted that. But one day he would take me from this living hell and I looked forward to that day.
And now I focus on placing one foot in front of the other. I must give this to him, my final gift. His birthday is soon and this will be my present to him. This will make up for all those birthdays I missed.
He has become so much more than I could have dreamed. I am dying now and I have never been more proud of him. And he must never know that I followed such monstrous orders. I can't bear the thought of him hating me for the right reasons. I deserve that hatred and it sickens me. But he is alive, my baby brother, and he is strong, so very strong. He must live. I fear I have hurt him more than I meant to. He must live.
I let Zetsu leave because he will report to Madara, who in turn will save my brother. But he will try to tell my brother the truth and that must never happen. I am sorry, but I must plant this within my gift. Know that it is because I love you, baby brother. I always have. Do not hate me for this. You are strong enough now. Return to your friends, that Uzumaki brat and the pink-haired girl who loves you. Let your love for them wipe me from your memories. Yes, that is my final wish for you, baby brother. Live and love and forget. You deserve happiness after what I have done to you. Please forgive me.