Sasuke Uchiha (うちはサスケ, Uchiha Sasuke) is one of the last surviving members of Konohagakure's Uchiha clan. After his older brother, Itachi, slaughtered their clan, Sasuke made it his mission in life to avenge them by killing Itachi. He is added to Team 7 upon becoming a ninja and, through competition with his rival and best friend, Naruto Uzumaki, Sasuke starts developing his skills. Dissatisfied with his progress, he defects from Konoha so that he can acquire the strength needed to exact his revenge. His years of seeking vengeance and his actions that followed become increasingly demanding, irrational and isolates him from others, leading him to be branded as an international criminal. After learning the truth of his brother's sacrifice and later proving instrumental in ending the Fourth Shinobi World War and being happily redeemed by Naruto, Sasuke decides to return to Konoha and dedicates his life to help protect the village and its inhabitants becoming referred to as the "Supporting Kage" (支う影, Sasaukage).
Sasuke is the second and youngest son of Mikoto and Fugaku Uchiha; they named him after Sasuke Sarutobi in the hopes that he would someday be just as strong of a shinobi.[9] Sasuke grew up in the shadow of his older brother, Itachi, a natural prodigy who many in the Uchiha clan and the village would constantly compare Sasuke and any of his accomplishments to Itachi. Sasuke himself adored Itachi, never passing up an opportunity to spend time with him. Although Itachi welcomed his company, letting Sasuke watch him train and taking him on adventures into the forests,[10] Itachi in return rarely helped Sasuke himself become a better shinobi; when asked, he would often instead poke Sasuke's forehead and promise to do so some other time. Sasuke found this annoying, but didn't allow it to blemish his high opinion of his brother.
On entering the Konoha Ninja Academy, Sasuke proved to be the standout of his class, consistently getting top grades.[11] However, he could never meet the same milestones Itachi had set, resulting in their father paying Sasuke little attention.[12] Aware of this neglect, Itachi, despite being increasingly busy, tried to stand in for their father by giving Sasuke the recognition he craved, at times even blackmailing Fugaku to spend time with Sasuke. As time went on, Itachi started becoming distant with and cold towards their family, culminating in a falling out with much of the Uchiha clan on their suspicion that he'd killed his best friend, Shisui Uchiha. Sasuke did not understand the reason for this, but he didn't mind the side-effect: his father began taking an interest in his development. Fugaku taught Sasuke how to perform the Great Fireball Technique, which he mastered in a week.[13] Fugaku stated his pride in Sasuke for this accomplishment, but at the same time encouraged him not to follow in Itachi's footsteps.
Sasuke, now one of the last surviving Uchiha, was alone. He spent the first few days after the massacre wandering his family's compound, reflecting on the people who were now gone, killed by Itachi. Sasuke decided to do what Itachi had instructed and dedicated his life to vengeance, having no other interest than bringing about Itachi's death. He threw himself into his studies at the Academy, making no efforts to form friendships and ignoring all of the girls' attempts to gain his affection. One of his classmates, Naruto, disliked Sasuke's cool personality and the attention he received, and developed a one-sided rivalry in his pursuit to prove himself just as good as, if not better than, Sasuke. For his part, Sasuke thought little of Naruto and was usually annoyed by his outbursts, but would, at times, secretly smile at how hard Naruto worked because of him. Ironically, for all the attention he received, Naruto was the only person among his peers who understood Sasuke due to the painful experiences he had.
Sasuke was a happy child, eager to please and be worthy of his family name.[14] This changed after his entire family was killed by Itachi, the person he most admired in the world. He became cold toward others, unmoved by and uninterested in what they do or think of him, choosing instead to keep to himself. He stopped using honourifics like "sensei" or "sama", something considered rude in the Japanese language. His only goal in life became to take revenge for his family's deaths and, by extension, acquire the power needed for that revenge, even if it meant acquiring an external power that wasn't his own.[15][16]
The pursuit of power, difficult enough on its own, is something that Sasuke repeatedly struggles with. Whenever he meets new people, he makes an evaluation of their abilities: those he perceives to be weaker than himself he arrogantly disregards, giving them as little attention as possible so that they won't hold him back; those he perceives as stronger he fixates over and tries to surpass, especially when he believes he should be their equal. As a member of Team 7 he is repeatedly exposed to Kakashi Hatake's philosophy that there is strength in teamwork. For a time, Sasuke accepts this, experiencing it first-hand on several of Team 7's missions. He even starts becoming attached to his teammates and starts to forget the vengeance he craved. But when he meets Itachi again in Part I and is summarily defeated, Sasuke decides the team is making him weak and chooses to leave them and Konoha entirely, focusing solely on himself.
Sasuke succumbs to his clan's Curse of Hatred.
Prior to Sasuke's defection, Kakashi tries to point out the contradiction in Sasuke's viewpoint: he is driven to gain power because he lost his family, yet sacrifices the family he still has (Team 7) in order to gain that power. In Part II, Sasuke allows Orochimaru to experiment on him as long as he becomes stronger, only to turn against Orochimaru for using him in the first place and acquires new teammates with abilities that could further his goals. Sasuke initially set a no-kill policy for himself and his team against those unrelated to his revenge. This was dropped as his hatred increased: at the Kage Summit, he slaughtered numerous samurai in cold blood and recklessly challenged the five Kage before killing Danzō Shimura; he tries to kill Karin and Team 7 when they impede or attempt to dissuade him from his objectives;[17] he allies with Tobi and Akatsuki when their goals align, but leaves them without comment when he no longer needs them. His abandonment of all his former loyalties and his criminal acts convince his former classmates that Sasuke is beyond salvation.
After his final encounter with Itachi, Sasuke is left uncertain about what course to take; Orochimaru hypothesises this indecision is due to Sasuke, for the first time, being without anybody to tell him what to do. From long contemplation, Sasuke decides that the desire for retribution that drove him for so long is the perfect solution to the world's problems: if a single individual, what Sasuke calls the "Hokage", is solely responsible for making the difficult decisions, killing and the like for the greater good, then everybody will be unified in their hatred of that individual. He volunteers himself for that responsibility and, in order to prepare himself, plans to eliminate what few friendships he still has, namely Naruto. But Naruto, by refusing to give up on saving Sasuke from darkness, demonstrates that their friendship is too fundamental to who Sasuke is and that it cannot nor should not be broken. On coming to terms with this, Sasuke stops fighting the many bonds he's made and chooses to die so the Curse of Hatred would die along with him. However, after further convincing from Naruto, Sasuke chose to live to find redemption instead. Afterwards, Naruto returned Sasuke's forehead protector, which Sasuke keeps on him during his long travels as a symbol of their friendship before passing it to Boruto.
One of Sasuke's most significant bonds is the one he has with his older brother, Itachi, who by merely being mentioned can elicit strong reactions from Sasuke's otherwise calm demeanour. Sasuke adored Itachi when he was a boy, enjoying his company above all others'; as an infant, he would cry whenever he was held by someone besides Itachi and would immediately be happy once held by his big brother again.[18] When Itachi murdered the rest of the Uchiha clan, Sasuke was crushed not only by the loss of his family but also by what Itachi told him: that he had never loved Sasuke. Sasuke devotes years of his life to avenging their family by killing Itachi, which Itachi encourages whenever they meet. Sasuke is accordingly careful not to follow Itachi's instructions too closely, such as by not acquiring a Mangekyō Sharingan, as he doesn't want Itachi to have the satisfaction. After Itachi dies in battle with Sasuke, however, Sasuke learns that the hateful older brother that Itachi seemed to be was all an act and that, in truth, Sasuke was the most precious person to Itachi; his murder of the Uchiha was done on the instructions of Konoha, in order to protect Sasuke. Sasuke becomes overwhelmed by this discovery and starts conspiring against Konoha and all its citizens for ruining his and Itachi's lives, knowing full well it isn't what Itachi would want him to do. He changes his mind after he is able to speak to a reincarnated Itachi, adopting some of Itachi's views: he decides to fight for Konoha's future so that Itachi's actions aren't made meaningless and bases his understanding of the "Hokage" around the decisions Itachi made. He also starts poking the foreheads of others as a sign of affection, something Itachi used to always do with him.
Sasuke first met Sakura Haruno when they were children in the Academy, where his good looks caused her to become infatuated with him, which later grew into love. On his part, Sasuke was aware that Sakura had feelings for him, but he showed no interest in her and considered her to be annoying. After they became teammates, they began to interact more and acknowledge each other's strengths and weaknesses, causing Sasuke to think of her as someone he needs to protect. Despite feeling grateful of how much she is willing to do to make him happy, he still abandons the prospect of being with her to pursue revenge and defect Konoha. By the time the Fourth Shinobi World War gets underway, Sasuke had becomes so consumed with hatred that he was willing to kill Sakura. After the war, a redeemed Sasuke apologizes to Sakura for how much he hurt her and she tearfully forgives him, allowing them to reconcile. They later maintain a long distant relationship while he pursues a journey of redemption. They later marry and have a daughter, Sarada.[19] As a father, Sasuke seems to be a loving and doting one, as he can never bear to see Sarada sad and is willing to do anything to make her happy. However, Sasuke tends to be emotionally distant with his family for the sake of his duties, though he feels a strong connection to them when they are apart. Sasuke loves his daughter dearly, as he puts her safety before his own,[20] and promises her to come home before returning on his travelling.[21] While Sasuke is happy in his marriage to Sakura, he enjoys teasing her by declining to show her affection.
During his time as a wanderer, Sasuke was a recluse, keeping contact with people to an absolute minimum and maintained his strong sense of pride; he is willing to help the villages if their problems are beyond their expertise but ignores their requests if facing insignificant issues. He also sometimes act independently on his own and helps the five nations, but does not even bother to interact with anyone during such instances, although he does leave strong hints he was responsible. On some occasions where does interact with others while helping out the Five Great Nations, his conversations are often one-sided where he speaks briefly before vanishing without giving the other person a chance to reply. He is also not above acknowledging significant events as he sent a note congratulating Naruto for his wedding. Acknowledging his mistakes and once free from hate and vengeance, Sasuke reverts back to the type of person he was prior to the massacre; being kind to others and displaying a sense of humour but maintaining his aloof exterior. Although publicly regarded as a hero for his role in the war, Sasuke feels that his crimes and imperfections out weigh anything heroic he has ever done.
As an adult, Sasuke becomes wiser and mature, as well as genuinely warm and caring, although he retains his habit of insulting others, albeit more comically than coldly, and mostly towards Naruto. Although he fulfills Itachi's wish for him to live and protect Konoha, his duty of protecting it from the shadows and investigating the mysteries of Kaguya leave Sasuke unable to spend time with his family, to the point where he failed to even recognise his daughter Sarada. Sasuke takes his duties as a shinobi and a father seriously: he spends most of his daughter's childhood investigating threats greater than Kaguya; he is protective of Sarada and is very supportive of her goal to become Hokage and not end up like him. Sasuke admits his mistakes as a father, but he has strong parenting skills, as he has faith in Sarada's abilities. Nevertheless, Sasuke loves his family dearly, as he tries to spend time with them when he is able to come home, and expresses pride in his daughter's growth and achievements.