Background Info.
History: Orochimaru tested Sasuke's abilities by having him battle hundreds of Sound ninja, a task he completed without taking a scratch and without killing any of them. About the latter, Sasuke remarked that the only person he wanted to kill was Itachi. Soon afterwards he attacked Orochimaru, deciding that there was nothing else that he could learn and that Orochimaru was unworthy of having his body or the Sharingan. Although Sasuke appeared victorious after a brief scuffle, Orochimaru was able to initiate the body-stealing jutsu. Sasuke, however, was able to reverse the process, absorbing Orochimaru into his body.
With Orochimaru gone, Sasuke went ahead to recruit Orochimaru's former test subjects to form a team to help him find and kill Itachi. He recruited Suigetsu Hōzuki, Karin, and Jūgo and dubbed his new team Hebi. Almost after forming Hebi, Sasuke had his team split up and learn Itachi's whereabouts. While searching, Sasuke was found by Deidara and Tobi. Using his Sharingan, Sasuke managed to counter most of Deidara's attacks, driving him insane with his pre-existing hatred for the Sharingan, which to him could not see his art. As a last ditch effort, Deidara used C0 to blow Sasuke and himself up. Sasuke however summoned Manda to shield himself from the explosion, at the cost of the great serpent's life. After recovering from his wounds, Sasuke and Hebi continued onto one of Akatsuki's lairs where Sasuke finds a crow clone of Itachi which tells him they will have their final at the Abandoned Uchiha Stronghold, leaving the rest of Hebi behind with Kisame.
Once inside, Itachi told Sasuke the history of their clan, of Madara Uchiha and the powers of the Mangekyō Sharingan. Once he finished, the brothers fought first in a battle of genjutsu, and in the end, Sasuke emerged victorious after successfully repelling the effects of Tsukuyomi. The two then switched to a battle of ninjutsu. During the battle, Itachi ignited the area in Amaterasu flames and almost burned Sasuke. Sasuke however managed to survive by using one of Orochimaru's techniques and surprised Itachi with his gigantic lighting jutsu Kirin. Itachi survived only by his use of the third and final Mangekyō technique, Susanoo.
Sasuke unconscious next to Itachi's dead body.
Having used his last chakra on Kirin, Sasuke was at Itachi's mercy, but Orochimaru violently reappeared through one of his snake summons in a final attempted to take Sasuke's body for his own. Itachi however had Susanoo seal him in a permanent genjutsu and despite being weakened continued towards Sasuke. Cornered, Itachi aiming for Sasuke's eyes, but instead poked Sasuke in the forehead and fell to the floor dead. Sasuke passed out from exhaustion moments later.
Sasuke wakes up in a cave in the care of Tobi, who was in reality Madara Uchiha. Madara tried to befriend Sasuke by removing his mask and revealing his Sharingan, something that caused Itachi's Mangekyō Sharingan to form in Sasuke's left eye and made him use Amaterasu on Madara, who quickly retreated into the darkness of the cave. After stopping the black flames, Madara then appeared again with his mask and began to muse about how Itachi never ceased to amaze him. As Sasuke asked what he was talking about, Madara revealed that Itachi had most likely set it up so that the sight of his Sharingan would trigger the Amaterasu he had sealed within Sasuke. As Sasuke complained that he was making no sense, Madara revealed that it had been to protect him, and, when Sasuke still didn't believe him, Madara said how it must all sound crazy, but assured him that he was telling the truth, and introduced himself as the man who had helped Itachi to slaughter the entire Uchiha clan.
Madara revealed to Sasuke the "truth" of Itachi, that he killed his clan by orders from Konoha, how he joined Akatsuki to keep an eye on the organization from the inside, and how in the end his only goal was to keep his village, and his brother safe. And that everything he had done was to make sure Sasuke grew strong. Remembering his childhood of how Itachi really was a kind, good brother, Sasuke developed his own Mangekyō Sharingan. He renamed Hebi to Taka and vowed he would destroy Konoha after crying over the memories of his beloved older brother.
Invasion of Pain Arc Edit
Sasuke caught in Killer Bee's Lariat.
Before Hebi, now renamed Taka, could attack Konoha, Madara convinced them to start working with Akatsuki. He sent them to the Land of Lightning to capture the Eight-Tailed Giant Ox, where they found its host, Killer Bee. The capture attempt got off to a bad start, as Killer Bee easily defeated both Suigetsu and Jūgo, and wounded Sasuke by impaling him in the chest with multiple swords. Sasuke was rescued and healed by Karin, and the team decided to all attack at once. While they had more success, Killer Bee released a great deal of the Eight-Tails' chakra and created a chakra cloak. When Sasuke's genjutsu failed on Killer Bee, the latter retaliated with great force, using the Eight-Tails' power to blow Sasuke's neck and chest apart.
While Sasuke was down, Killer Bee fully transformed into the beast sealed within him, leaving Taka outclassed. Suigetsu then sacrificed himself to give Jūgo time to heal Sasuke by fusing some of his own flesh with Sasuke's. Fearing the deaths of his team-mates, Sasuke unleashed his new Mangekyō Sharingan and Amaterasu to capture Killer Bee. Sai would later state that due to this incident, Sasuke would never be accepted again as a citizen of Konoha.
Sasuke delivered Killer Bee to Madara (although this was later discovered to be a fake) before regrouping with Taka. While resting, they dealt with a Kumo ninja who had been following them. However, when Sasuke tipped over a glass of water, he learned that his eyesight was already starting to deteriorate. He opted to keep this revelation from the team.