obviously orochimaru!! i loath the guy with a passion- if it wasn't for him putting that curse mark on sasuke then he woudve never have left and if he didn't get the sound ninja 5 to get sasuke then he may have never left as well- obviously. he wasnt in the right mind-state and they took advantage of that! it makes me sck to think of orochimaru's whole immortality jutsu and how he just uses everyone as his pawns and when they are no longer of good use he just thows them away like nothing!! i can understand why some people dislike sasuke but i just can't- i admit i found him quite irritating at first with him thinking he was superior to everyone and having such an attitude all the time, but ive come to like the guy and i understand him a bit better- even though hes now with orochimaru i know the real sasuke is still in there- in the darkness- just like neji and gaara was- naruto managed to take them out of the darkness and with a bit more work im sure he can help sasuke too.