Itachi Uchiha

Itachi Uchiha (うちはイタチ, Uchiha Itachi) was an ANBU Captain and a prodigy from Konohagakure's famed Uchiha clan. He had joined the criminal organisation Akatsuki to serve as a double-spy, to later become an S-rank missing-nin as he participated in murder of his entire clan on orders from higher-ups, in what would become known as the Uchiha clan massacre, defecting from the village subsequently.

Source: http://naruto.wikia.com/wiki/Itachi_Uchiha

Background

Itachi holding his baby brother, moments before the Nine-Tails' attack on Konoha.

Itachi was born into the Uchiha clan as the eldest son of Mikoto and Fugaku Uchiha, and was praised by all as the best of his generation, and a genius above all others. Even by the standards of the battle-adept Uchiha clan, Itachi's prowess far outshone their own. However, few could understand him. When he was only four, Itachi had already witnessed countless lives lost due to the Third Shinobi World War, which emotionally traumatised him and consequently turned him into a pacifist. Itachi spent much of his time researching the history of the village from the writings their ancestors left behind.
During the Nine-Tails' attack on Konoha, Itachi was left alone to take care of his infant brother Sasuke and promised to protect him no matter what. In the anime, it was shown that during their childhood, Itachi made a game of collecting paw prints of cats with his brother. The last paw print to be collected was Nekomata's, who Itachi had defeated and asked him to fight Sasuke with all his might when Sasuke got older.
At age 7, Itachi graduated from the Academy at the top of his class after only one year, mastered the Sharingan at age 8, passed the Chūnin Exams at age 10, enrolled in ANBU half a year later and became captain by 13. At some point in time in their childhood, Sasuke helped Itachi on one of his missions to capture a giant boar. Itachi told Sasuke to avoid his vital points. He then threw kunai with explosive tags around the boar, to confuse it and to give Sasuke an opportunity to shoot the boar. Sasuke, however, missed completely. After Sasuke apologised, Itachi told him he needs to train more.
Itachi was praised highly by Fugaku, his father, who spent most of his time grooming Itachi to inherit the title of leader of the Uchiha, and hence inadvertently neglected his younger son. However, during this time Itachi showed great affection towards his little brother and even encouraged his father to come to the Academy enrolment ceremony for Sasuke, something their father had otherwise forgotten, caught up an important mission that would establish Itachi a place in the ANBU ranks.

A young Itachi with his family.

When the Uchiha clan began planning to overthrow Konoha, Itachi, as an ANBU, was tasked with spying on the village. Knowing that a coup d'état would only escalate to the beginning of another ninja-world war, Itachi began spying on the Uchiha instead, passing on information to the Third Hokage and Konoha elders. Though the Third Hokage ultimately decided to reason with the Uchiha in order to dissuade them from their actions, Danzō Shimura met secretly with Itachi Uchiha and inveigled him into choosing the lives of his clansmen or that of his little brother. Itachi eventually discovered the existence of Tobi — under the guise of a vengeful Madara Uchiha — who was attempting to rekindle the flames of war in Konoha. In return for not attacking Konoha, Itachi offered to help him claim vengeance against the Uchiha for turning their backs on him decades earlier to which Tobi agreed. Itachi joined Akatsuki, but did so in order to keep an eye on the organisation.. During his time in Akatsuki, Orochimaru tried to steal his body to gain the Sharingan, but Itachi trapped him in a genjutsu and severed his left hand.
Itachi was later partnered with Kisame Hoshigaki, who initially tried to intimidate him. However, they eventually became good partners. During this time he began to act strangely, not attending the clan meetings, speaking out against the clan, and becoming the prime suspect for the murder of his best friend Shisui Uchiha, who was drowned in the Naka River. In reality, Shisui died after he entrusted his left eye to Itachi, the other having been taken by Danzō Shimura during Shisui's failed attempt to stop Danzō from carrying out his plan to commit genocide. Due to this the clan lost hope in Itachi, and his father began shifting his focus to Sasuke instead. Meanwhile, the Third's attempts to negotiate a bloodless end to hostilities between the two parties were proving ineffective, so against Hiruzen's wishes, Danzō Shimura and the Konoha Council ordered Itachi to wipe out the Uchiha clan.

Itachi shows Sasuke how he slaughtered their parents.

Before the fateful night arrived, Itachi with the help of Tobi under the guise of Madara Uchiha slaughtered his entire clan overnight . Despite this action, his parents stated that they were still proud of their eldest son, and requested that he took care of Sasuke. Itachi spared Sasuke because he loved his little brother, and as per the agreement between him and Danzō, did not want to take the life of the person most important to him. He lied to his brother, making himself out as a villain who had killed their innocent family only to test his capacity, and told Sasuke he was not even worth killing. Itachi also revealed to Sasuke the secret meeting place of the Uchiha, where Sasuke can learn the true history and purpose of the Sharingan. Itachi told him that in order to awaken the Mangekyō Sharingan, Sasuke had to kill the person closest to him, and that when they met again, they should have the same eyes.

	Itachi pleads with the Third to protect Sasuke.

Sasuke managed to stand back up, awaken his Sharingan, and pursue Itachi. Upon reaching Itachi, he managed to knock off his forehead protector. Itachi shed a tear as he was picking up his forehead protector, then proceeded to incapacitate Sasuke, who awoke in the hospital, only remembering up to Itachi's speech. Hoping that his little brother would someday be powerful enough to kill him, Itachi left the village as a traitor. Knowing that Konoha would still want to eliminate Sasuke, Itachi pleaded with the Third Hokage to keep Sasuke safe and threatened Danzō not to harm Sasuke or else he would reveal everything he knew about Konoha's secrets to enemy nations.
Sometime later, Itachi helped recruit Deidara by beating him in battle using only genjutsu, to which Deidara swore vengeance. As well at some point in time, Itachi contracted a fatal disease. He kept himself alive through the intake of various medicines, and sheer "willpower", in the hopes of living long enough to die by Sasuke's hands.

Personality

Itachi shedding tears as he leaves Sasuke.

Itachi had always been an inscrutable individual. Unlike the vast majority of his clan, Itachi was not interested in personal gain for their clan, Itachi cared not only for them but for the village as a whole. Flashbacks showed that he used to be a compassionate brother, but his initial appearances depicted him as an Akatsuki criminal interested in the organisation's success and secrecy before all else. Later his interest in Akatsuki was revealed to be an act, and his true intentions for joining the organisation were to spy on it from within. Nonetheless, Itachi and his partner, Kisame, cooperated better than most Akatsuki partners, and despite the differences in personalities, appeared to have mutual respect for one another.

Itachi poking Sasuke — something he did regularly.

Itachi was shown to be highly perceptive, analytical, and intelligent, something even Tobi acknowledged. He was very quick-witted, controlled, disciplined and clear-headed, showing a great maturity, responsibility and intuitiveness; rarely being caught off guard or deceived. Itachi had great foresight; his foreknowledge of Sasuke's victory against Deidara, his own pre-meditated death by Sasuke's hand, and the implantation of the Kotoamatsukami-imbued crow inside Naruto were some examples seen. Even from a young age, Itachi was noted to be wise beyond his years and spent much of his time researching the history of the village from the writings their ancestors left behind. From this, by the age of seven, his understanding of the world was on par with that of a Hokage.
While Itachi was a powerful shinobi, he showed great humility and often-time commended his opponents on their abilities. Likewise because of his pacifist nature, Itachi took no enjoyment in violence or combat, instead preferring to avoid battle or, if not possible, end it as quickly as he could. Because of his respect for the village's history, Itachi was never limited to the view of his own clan but worried about the fate of the village as a whole. While a disgraced man who has lost all he holds dear, Itachi remained a very dutiful and selfless individual, caring only for both his village and little brother's well-being; having never fallen victim to his clan's inherited Curse of Hatred that would normally follow such a loss combined with the awakening of the Sharingan. Itachi's devotion to his village seemed to generate one flaw in his personality; his inability to trust other people's strength. It was this flaw that caused him to decide to manipulate Sasuke into the shinobi he wanted Sasuke to be, an act he later decided was a mistake. It was not until after his death that he realised this and began to trust other people, going as far as to show Sasuke the truth so that he can walk his own path without anyone else's interference as well as vowing to always love Sasuke no matter what path he took. Itachi also possessed incredible control of his emotions, only showing surprise when opponents proved more powerful than expected, and even then did not lose his composure. After his death, he has been shown to have a dry, laconic sense of humour, even under stressful situations, such as questioning Naruto's claim that no one could survive Nagato's attack when Naruto clearly did, and calling his younger brother a "snake expert" while fighting Kabuto Yakushi.

Itachi shaking and crying as he is about to kill his parents.

As Kabuto noted, Itachi lived in deception. On top of his pretence in promoting Akatsuki's goals, he also pretended to seek the Eternal Mangekyō Sharingan. During a genjutsu fight with Sasuke, he claimed to have only let Sasuke live to take his eyes, and that the Uchiha clan had been tainted and corrupt, since clan members would kill their friends to obtain the Mangekyō Sharingan and transplant another Uchiha clan members' eyes to make the power permanent. Once the genjutsu was released, he called it his true self, implying his emotionless personality was also a façade. This personality was later revealed to be an act to ensure that he would die by Sasuke's hands. After learning Sasuke refused to go back to Konoha post-mortem, Itachi placed all his faith in Naruto, who he noted had inherited Shisui's will and was determined to save Sasuke. Despite all his treacherous actions, Itachi only did them all to protect Sasuke and Konoha. Finally, even while knowing the dark sides of the village, he still considered himself a shinobi of Konoha and was even happy he was able to serve his village one more time after his reincarnation. Along with Sasuke, Itachi also dearly loved his parents, Fugaku and Mikoto Uchiha, even though he disagreed with their plans. When he was forced to kill them, having put them off for last, Itachi wept and shook violently as he committed the act: strongly hinting that he felt only enormous guilt and remorse.

Appearance

Itachi's appearance after joining Akatsuki.

Despite his status as an infamous shinobi, Itachi's appearance was not the most intimidating, apart from the intensity of his gaze. While living in Konoha, he would regularly have a gentle look in his eyes, especially directed towards his younger brother. After joining Akatsuki, they would regularly have a stern look to them.
Itachi was a young man with onyx eyes, and jet-black hair that was pulled back with a red elastic in a low ponytail which extended to his shoulder blades. The ponytail was, however, later obscured by the high collar of the Akatsuki cloak he wore after joining the organisation. He also had centre-parted bangs that framed his face, extending to his chin. When grown up, Itachi's most distinguishing feature were the long, pronounced tear-troughs under his eyes. Itachi and Sasuke also bear similarities to one another in terms of their appearance as Naruto nearly mistook Itachi for Sasuke when they first met, while Tobi and Kisame commented upon their resemblance when they first encountered Sasuke.
When he lived in Konoha, his casual clothes consisted of a black shirt with the Uchiha clan symbol on the back with bandages around his ankles and black sandals. He also wore tan pants with a weapons pouch strapped to his back. While his hair was still worn in a ponytail, his bangs were considerably shorter; accentuating his forehead in a manner similar to Kabuto Yakushi's hairstyle in Part I and for a majority of Part II. When on duty, he would wear the standard ANBU uniform complete with arm guards, a flak jacket, and a porcelain mask which was fashioned to resemble a weasel with a dark, triangular marking on top. As a member of Akatsuki, he wore a slashed Konoha forehead protector and the standard Akatsuki cloak. Sometimes, he would unbutton his cloak to mid-chest and rest his left arm there, rather than in the sleeve. After his cloak was incinerated by Sasuke's Kirin during their fight in Part II, it was revealed that he wore similar clothes to that of the rest of Akatsuki. His attire consisted of mesh armour with navy accents under an identical T-shirt with a simple white belt around the waist, and dark blue pants. Like most members of Akatsuki, he wore the forehead protector of his home village with a horizontal line gouged through it to symbolise his broken ties with the village. On his right ring finger was his Akatsuki ring, which was red and bore the kanji for "vermilion" (朱, shu). He also wore purple nail polish on his fingers and toes and a necklace which had three silver rings with red gems inside them.
After being reincarnated, Itachi's eyes appear to have black sclerae like the other shinobi that Kabuto reincarnated, and was clad in a dark-red cloak.

Abilities

Itachi's usage of crows in genjutsu.

A child whose genius manifested at a young age, Itachi's teachers at the Academy noted that his progress hardly required any help, having been quickly promoted through the ninja ranks while still a child, further showing his remarkable capacities. In his battles, Itachi was shown to be an immensely powerful ninja and gained praise from allies and foes alike. During his battle against Kakashi Hatake, Kurenai Yūhi, and Asuma Sarutobi, Kakashi commented that Itachi was not fighting with even half his strength. Even Orochimaru, a former fellow member of Akatsuki, openly admitted Itachi was stronger than him. Tobi has also stated that Itachi never ceased to amaze him. Despite his own impressive abilities, Itachi never underestimated his opponents, given his praise of Jiraiya, in which he noted to Kisame that, provided he had the latter's help, if he fought Jiraiya, they would either kill each other or Itachi himself would lose.
As an Uchiha, Itachi had very strong chakra. However, he had low supplies of chakra which made him unable to participate in prolonged battles. In Part I, he could only use the Mangekyō Sharingan for a maximum of three times in a day before he needed a significant amount of rest. Even with that, and Itachi's health failing, along with the fact that he was holding back, Sasuke still could not defeat him during what would be their final confrontation with Itachi controling the direction and outcome of the battle. Being a technical pacifist due to traumatic experiences from the Third Shinobi World War, Itachi did not actively take part in battle, only acting in self-defence, and mostly incapacitating his enemies instead of killing them if possible.