History: Sasuke is the second and youngest son of the Konoha Military Police Force captain and Uchiha clan head: Fugaku Uchiha, and his wife Mikoto. Mikoto named him after the father of the Third Hokage in hopes that he would grow up to be a great ninja like his namesake. As a child, Sasuke grew up in the shadow of his older brother, Itachi Uchiha who was an acknowledged prodigy viewed by the Uchiha clan as a genius, and whose work would further strengthen the bonds between the village and the clan. Sasuke's father in particular took an active interest in Itachi. Itachi, on the other hand, was rather ambivalent and full of oddly conflicting undercurrents, acknowledging Sasuke by taking interest in his progress as a ninja and spending time playing with him when even their father did not. Even after Sasuke enrolled in the Academy, he was still unable to escape Itachi's shadow. Despite consistently scoring at the top of every class, Sasuke failed to receive any recognition from his father, who defined Sasuke's success only in terms of his older brother. Itachi acknowledged the rivalry Sasuke felt telling him: "We are brothers. I am the wall you must climb over, so you and I will continue to exist together." Nevertheless Itachi deeply cared for his younger brother and Sasuke looked up to Itachi, wanting to be more like him.
The relationship between Itachi and his father deteriorated further after Itachi was questioned by other members of the Uchiha clan regarding the apparent suicide of his best friend, Shisui. As Itachi's behaviour became increasingly bizarre, Sasuke's father began spending more time with Sasuke, and began teaching him the Great Fireball Technique, a common family technique seen as a sign of coming of age in the Uchiha clan. When Sasuke first tried to perform the technique, he only produced a small flame and after that, some smoke. His father said that Itachi was able to do it on his first try at Sasuke's age, which disappointed him. Later, with one week of training, Sasuke (age 7 at the time) performed the technique in front of his father, proving himself a genius as well in his own right and finally receiving his father's recognition. Sasuke's father told him that he could now proudly wear the clan's emblem on his back. Following this, Sasuke also received a stern warning not to follow in Itachi's footsteps any further, surprising him as before, he was told to be like him; and his father showing he was proud of Sasuke for the first time the same way as he used to with Itachi.
At some point in the past, Sasuke joined Itachi on a mission to catch a wild boar. Sasuke was wielding a bow and was told by Itachi not to hit any vital points. However, Sasuke missed the boar completely. Eventually they defeated the boar and Sasuke apologized for being so off, Itachi responded by telling him that he needed to train more.
On one fateful night, Itachi slew every member of the Uchiha clan, sparing only Sasuke, saying that he was not even worth killing. In addition, Itachi told him, "You've always wanted to surpass me. That's why I'm going to let you live… if you wish to kill me, then hate me, despise me… and by all means flee, cling to your wretched life." Itachi also revealed to Sasuke where the secret meeting place of the Uchiha was hidden, and suggested that Sasuke go there to learn what the true history and purpose of the Sharingan was. He told him that "to awaken the Mangekyo Sharingan," he "had to kill the person he was closest to", and that "when we battle, we should have the same eyes". Sasuke thought he had fainted after this, but later remembered that he had managed to stand back up, awaken his Sharingan, and pursued Itachi. Upon reaching Itachi, he used knives to knock off his forehead protector. Itachi was seen shedding a tear as he was picking up the forehead protector. He then proceeded to incapacitate Sasuke, who awoke in the hospital remembering only that which Itachi wanted him to.
When Sasuke first met Naruto Uzumaki in the Academy, they were matched to spar against each other. Naruto was excited at the opportunity to defeat Sasuke and become so popular like him, however he was easily beaten. By looking at Sasuke's eyes, Naruto realised that they were so filled with hatred that it seemed that he wasn't even looking at Naruto. When Iruka told them to make the reconciliation seal, they both refused. Up until his graduation from the Academy, Sasuke remained a loner and never acknowledged Naruto's attempts to defeat him, considering him a hopeless dead-last and as such, someone not worth his time or energy.

Upon the formation of Team 7, Naruto, Sakura and Sasuke were forced to mingle. Sasuke tried to avoid both of them, but he kept getting drawn into Sakura and Naruto's antics. Accordingly, Kakashi gave them a bell test, the three of them being tasked with taking the two bells he kept on his person. Sasuke tried to take a bell by himself, ignoring his team-mates in the process, failing regardless of having a better success rate. Regrouping with his team, they all realised that the true goal of the test was to learn to place teamwork above the single-handed completion of the mission, and, in doing so, were allowed to pass.
Sasuke's first major mission was escorting the bridge builder, Tazuna, to his home in the poverty-stricken Land of Waves. Soon after setting out, Sasuke showed exceptional skill when attacked by the Demon Brothers, even taunting Naruto for being shocked and useless during this encounter. When they later had a tree-climbing exercise to improve chakra control, he managed to stay ahead of Naruto for a good length of time, but as Naruto began to catch up, they started to push each other's limits. His skills improved, Sasuke was almost able to compete with Haku, who was extremely dangerous because of his extreme speed and dexterity. It was during this battle that Sasuke reawakened the legacy of his clan, the Sharingan, and even selflessly put himself in the way of Haku's attack on Naruto to protect him. Although he claimed his body had moved on its own, his actions showed that he was willing to put himself in mortal danger for Naruto's sake. Although it appeared that Sasuke had died in the process, it was later revealed that he was merely put in a temporary death state.
Before the Chūnin Exams started, Sasuke fought Rock Lee, who uses his speed to defeat him with his and taijutsu prowess. However, before the finishing blow could be given, Might Guy interrupted the match and punished his beloved student for using a forbidden technique in a normal fight. In the first part of the exam, Sasuke realised that, to succeed in the written test, it is required to cheat without getting caught, using his Sharingan to copy the pencil movements of a student in front of him, effectively copying the answers.
In the second test of the Chūnin Exams in the Forest of Death, Sasuke was attacked by who he thought was Kusagakure genin Shiore. However, with Naruto urging him not to surrender to the stronger ninja, Sasuke defeats who he learns is actually the missing-nin Orochimaru who implants his cursed seal on Sasuke's neck as a reward. Losing conscious from the immense pain of the seal as it attunes to his body, Sasuke suffers horrific nightmares before awakening under its influence as he mercilessly defeats Otogakure genin and breaks Zaku's arms. It took Sakura's hug and pleas to snap him back to normal. In a flashback detailed Part II, Sasuke is revealed to have met Karin while saving her from a bear, letting her be as he didn't need her scroll.

Sasuke's match up in the preliminaries was against Yoroi Akadō. Before the fight started, Kakashi warned Sasuke that, if his cursed seal got out of control, which would happen if he used any chakra, he would need to be removed from the competition. The match started with Yoroi absorbing what little chakra Sasuke had left through his hands, and with Sasuke being in constant pain from his cursed seal. Having only one option, and remembering his previous encounter with Rock Lee, Sasuke used the Lion Combo. Yoroi was knocked out, and Sasuke advanced to the next round.
Following his win, Kakashi took Sasuke away to seal the cursed seal, but made it a point to tell him that the seal would only remain active as long as Sasuke wanted it to. Not convinced that his words would deter Sasuke from using the cursed seal, and turning to Orochimaru, Kakashi used the month leading up to the final rounds to teach him the Chidori. At the same time, knowing Sasuke would be facing Gaara, he helped Sasuke to emulate some of Lee's speed. After showing up late for his match with Gaara, Sasuke demonstrated the fruits of his training, even managing to break through Gaara's defences and injure him. Before the match could finish, however, it was interrupted by the start of Orochimaru's attack on Konoha.
With the start of the invasion, Gaara fled the village with his siblings, and Sasuke was sent after them by Genma. Sasuke chased them and, after short battles with Kankurō and Temari, caught up with Gaara before fighting him again. However, Gaara utilises his jinchūriki powers to overpower Sasuke before Naruto take over the fight and defeats Gaara. Later attending the Third Hokage's funeral, witnessing Naruto's strength injured Sasuke's pride as he becomes envious of him.
After the failed invasion, Sasuke went to see Kakashi, and later was seen reading the stone tablet in the Naka Shrine. When he arrived at Kakashi's house to see him again, he found his teacher in a coma. Although nobody in the room was willing to tell Sasuke of what had happened, Aoba Yamashiro soon arrived and let slip that Itachi had returned to the village in search of Naruto. Determined to find Itachi, Sasuke tracks Naruto down and finds his brother there. Despite his best efforts, including the use of Chidori, none of his attacks were able to hit Itachi. Itachi tormented Sasuke physically and mentally, belittling him for still being too weak, eventually leaving Sasuke with a broken wrist and mind. Sasuke then fell into the same Tsukuyomi-induced coma as Kakashi. Guy appeared to take Sasuke back to Konoha, however, it was not until Tsunade returned to Konoha that he recovered.

Motivated by rage over Itachi still being stronger, and his jealously to his team-mate for becoming stronger in short period of time, Sasuke forces Naruto into fighting him before Kakashi stops the two as they use their strongest attacks on each other. Although thinking his Chidori did the most damage to a nearby water tower, Sasuke is shocked to find Naruto's Rasengan obliterated one whole side of it without the structure compromised. After being lectured by Kakashi over not using Chidori on his own friends, Sasuke was confronted by Orochimaru's Sound Four, who have been sent to bring to him to Otogakure. Revealing himself and his comrades being branded with cursed seals with full mastery over them, Sakon leaves Sasuke with the offer to come with them if he wishes to use his cursed seal's true potential. Deciding to take Orochimaru up on his offer, Sasuke is confronted by a shocked Sakura as he sneaks out of Konoha. Despite Sakura's desperate pleas, Sasuke thanks her before knocking her out and joining up with the Sound Four, who soon afterwards advanced his cursed seal to its second level, a process that left him unconscious for most of their battle with the Sasuke Retrieval Team.
Soon after Sasuke woke up, he ran his way towards the Valley of the End where he is found by Naruto, who had learned Orochimaru's intent to turn Sasuke into his next host. Seeing Naruto, Sasuke reveals his intents to kill him to obtain the Mangekyō Sharingan. Naruto refused to accept that Sasuke would do this or his other reasons for pursuing Orochimaru, choosing instead to drag Sasuke back to the village by force if needed. With Sasuke gloating that Naruto can not even make a scratch on his forehead protector, he initially having the upper hand thanks to his cursed seal and Sharingan. When he managed to pierce Naruto's right shoulder with his Chidori, however, the Nine-Tails' chakra kicked in to protect Naruto, giving him a massive power increase as he attempt to knock some sense into him. Sasuke merely retorted that Naruto could never understand losing a family as he had never had them to begin with, despite Naruto feeling that Sasuke is like a brother to him and refuses to let him destroy that bond. Sasuke's Sharingan evolved to its final level at that point, tipping the battle in Sasuke's favour because he was able to predict Naruto's movements. However, Naruto's Nine-Tails' chakra envelops him in a fox-shaped shield of chakra.
In response, Sasuke activated the second stage of his cursed seal as both he and Naruto clash with their respective empowered attacks. Clashing with the dome produced from the conflicting energies, Sasuke defeats Naruto with a punch to the chest rather than what remained of Chidori. But before the dome dissipates while losing consciousness, Naruto managed to scratch Sasuke's forehead protector as it falls off of him. Though considering to kill Naruto then and now, Sasuke begins to have second thoughts and resolves to find his own way to surpass Itachi. Leaving behind his scratched forehead protector, which had fallen off after Naruto's last attack, Sasuke made his way to Orochimaru, who decides to train Sasuke until the time to make the youth his new host comes.

Almost three years after leaving Konoha, Sasuke meets his replacement in the renamed Team Kakashi, Sai. Despite a lack of interest in Sai, Sasuke is inadvertently provoked and subjects Sai to a genjutsu exuding a large amount of killing intent. Sai is amazed that even an emotionless person such as himself was affected by Sasuke's gaze, channelling through his Sharingan. When Sai comments on how Naruto and Sakura have been searching for him, Sasuke once again regards him with indifference in attitude. Later, when Team Kakashi infiltrates one of Orochimaru's hideouts successfully under the leadership of Yamato, Sai, acting on his own, locates and enters Sasuke's room while he was resting in a bid to assassinate him as ordered by his superior in Konoha's Root faction, Danzō Shimura.
However, after spending quality time in Team Kakashi, especially with Naruto, Sai comes to understand the meaning of bonds of friendship, and decides to help Naruto save him. However, enraged on being disturbed, Sasuke destroys the room, drawing Naruto, Sakura and Yamato to their location. Despite this being the first time in nearly three years that they had seen each other, Sasuke expresses his usual indifference towards his former team. Unperturbed of Orochimaru's intentions for him and the prospect going home to Konoha with his former friends, Sasuke engages them in battle, showing off his increase in speed and improved abilities.
Team Kakashi are ultimately outmatched against Sasuke, mostly due to the team's exhaustion with Naruto's four-tailed form (that he had previously used to battle Orochimaru), causing Naruto to begin struggling with Kurama in his mind. To the surprise of both Naruto and Kurama, Sasuke uses his heightened prowess of his Sharingan to enter Naruto's subconscious to meet the Nine-Tails itself, finally discovering the true source of Naruto's strength. Kurama appears to be impressed with Sasuke's growth and ability as it states his chakra being as "sinister" as Madara Uchiha's. Sasuke coldly dismisses knowing such a person and uses his Sharingan to suppress Kurama back into its sealed cage. Kurama concludes that this would probably be its last meeting with Sasuke, so it warns him not to kill Naruto, for he would only end up regretting it. Back outside, Sasuke decides to finish off his former team-mates, starting with Naruto, only to be stopped by Orochimaru as the prospect of them and other Konoha shinobi thinning out the Akatsuki would make his revenge easier. Accepting the notion, Sasuke leaves with Orochimaru and Kabuto.