Sasuke Uchiha is a main character in Naruto, serving as a secondary protagonist in early Part I and later as an antagonist in majority of Part II before redeeming himself in the end. He is Sakura Haruno's love interest.
Sasuke was part of the Uchiha clan, one of the most powerful ninja families in Konoha. He grew up admiring his brother Itachi, but one night he found his entire clan had been slaughtered by his big brother. This traumatized him and he devoted himself to his ninja studies in the hopes of getting revenge against Itachi and restoring his clan.
While Naruto was a social pariah, Sasuke was accepted by everyone. His good looks, effortless talent and detached personality made him popular with the girls, though he never showed any interest. After Itachi returned to their village, Sasuke tracked him down and tried to kill him, only to be tossed aside and left to think about how little he has achieved. Sasuke then decided to leave Konoha and seek tutelage under various rogue ninja.
After defeating Itachi, Sasuke finds out the truth about his clan: they were wiped out on the orders of Konoha because they were too powerful to be trusted and were planning to overthrown the village to exact revenge for years of ostracism. Itachi was given the task of carrying out the massacre with only sparing Sasuke out of love. Enraged, Sasuke declares vengeance on Konoha and briefly joins forces with Akatsuki. However, his hatred grew so strong he never showed mercy to anyone, not even members of his own team Taka. He is intercepted by Naruto and Sakura, who beg him to come home and let go of his hatred but he refused by denouncing any bond with them and he intended to kill them for simply being shinobis of Konoha and to erase any connections the village had to the Uchiha. After Sasuke kills Danzo, a Konoha elder who ordered the massacre, and nearly kills Sakura after she attempted to kill him to stop him from igniting a war among the nations, the only one left with any faith in Sasuke is Naruto.
Sasuke soon encounters a reanimated Itachi, who tells him more details about his actions, which cause Sasuke to question the the meaning of being a shinobi. He learns further revelations about his clan, namely that they are prone to violence after experiencing generations of suffering under the leadership of Madara Uchiha. Sasuke's generation was originally meant to be one that could co-exist with other ninja, but when rumors of the Uchiha planning to take over the village started spreading, the village elders decided to have Itachi kill them all but allowed him to spare Sasuke, and Itachi assumed the role of a criminal and always intended to die by Sasuke's hand as punishment. Sasuke, realizing that the cycle of hatred would only stop if he could learn to let go of his hatred, decides against destroying the village and allies himself with Naruto and the others. He announces his choice to become Hokage so he can change the ninja world and prevent future chaos.
After defeating Madara and later Kaguya, Sasuke considers taking their place so that the ninja world will have an enemy to keep them from turning on each other once again. Naruto clashes with Sasuke, who intends to kill Naruto, the one person to stop him fulfilling his goal. However their powers are too even to determine an outcome and both ultimately lose arms in their battle. Seeing how committed he was even after all that had happened, Sasuke came to the conclusion that they were too similar to be fighting and made his peace with Naruto. He is pardoned for his crimes by Kakashi due to his service in ending the war and a good word from Naruto, and reconciles with his former friends and comrades, and even showed interest in starting a relationship with Sakura. He then spends the rest of his life traveling the ninja world fighting injustice.
While he has the affection of almost every girl he knows, Sasuke has only shown romantic interest in Sakura and even then it wasn't until the very end of the series.
Sakura has always had a crush on Sasuke since they were very young, although Sasuke often dismissed her. After being assigned to the same team as him, Sakura neglected her ninja training and spent more time trying to woo Sasuke. During their time together in Team 7, Sasuke was shown to have developed a soft side for Sakura, to the point where he told Naruto to do eveything in his power to save her from Gaara and expressed jealousy when Sakura smiled at Naruto from saving her at one point. This side was shown again when Sasuke caught her as she was about to collapse during the fight against Kaguya. It has been revealed that both Sakura and Sasuke can read each other easily. He has even admitted that without his Sharingan, his genjutsu abilities are inferior to Sakura's though Naruto doesn't go into this much. When Sasuke made plans to leave Konoha, Sakura tried to stop him by confessing her love for him, only for Sasuke to thank her for everything she's done for him and leave anyway.
Three years later, Sakura slowly began to realize that Sasuke is no good for her, but she still remained in love with him to the point where she assaulted anyone who bad-mouthed about Sasuke. As Sasuke fell deeper into darkness and became an international criminal, a distraught Sakura resolved to kill him in order to prevent him from starting a war among the nations. However, Sasuke saw her as nothing more than a shinobi that was from the village he blamed for his clan's demise and tried twice to kill her, making her realize it was hopeless to save him. Despite this, she remained in love with him. When Sasuke allied himself with Naruto and the others, Sakura, although happy he's back, didn't trust him; which was confirmed when Sasuke announced his intent to start a revolution by killing the current Kage and the tailed beasts in order to become the world's sole enemy. Sakura again tried to convince him to return home by confessing her love before he knocked her out. Sasuke said he saw no reason for him and Sakura to love each other and he believed her feelings were from a failed past. After his battle with Naruto, Sakura arrived to heal them and Sasuke, redeemed and guilt-ridden for the pain he put Sakura through, sincerely apologized to her, which she accepted after some hesitation.
After being pardoned and before leaving for his journey of redemption, Sasuke declined to let Sakura join him but expressed an interest in starting a relationship with her by poking her on the forehead (which is dubbed the ultimate expression of love) and promised to see her again when he returns. A couple of years later, Sakura convinced Sasuke to let her accompany him on his traveling. During which, they got married and Sakura became pregnant with his child and she gave birth to a daughter, whom they named Sarada. The birth of his daughter symbolized the restoration of his clan, which had always been his goal. They lived together as a normal family for a couple of years before Sasuke left home for an important mission that would take him away from his family for years. Despite the distance, Sasuke regards Sakura and Sarada as the two most important people to him and their marriage turned out to be a good one.
Kishimoto has stated that Sasuke was always grateful to Sakura, that even though he had to leave, even though he caused her so much pain, he was still thankful from the bottom of his heart.
Just like Sakura, Ino has had a longtime crush on Sasuke. Her crush on him caused her friendship with Sakura to go sour and they became rivals. After Sasuke's defection, Ino seemingly gives up on him, but still feels upset at the thought that they might have to kill him. She also secretly fantasizes about Sasuke fighting for her affection, showing that her feelings never did fade away. Years later, it's revealed that Ino married Sai and had a son.
When Sasuke forms a team to help him track down Itachi, he enlists in Karin as part of Team Hebi and later Taka because of her sensory abilities. Karin has lusted after Sasuke ever since he saved her life years ago, although he rejected her advances. When Karin was held hostage by Danzo, Sasuke stabbed right through her to get to his target and called her a burden, and was willing to kill her. After that, Karin decided she'd had enough of Sasuke's abuse, only to fall for him all over again when he simply apologized. Years later, after Sasuke marries Sakura and has a daughter, Karin says she accepts he is happy with his family, and admits her friendship with Sakura and her fondness for Sarada.
- Sasuke's character revolved around love; he found it to be a weakness and tried to push it away. It was later revealed that it was something he wanted the most but cast it aside for the sake of his ambition. Now he has a family and he protects them dearly.
- At the end of the war, Sasuke is shown reciprocating Sakura's feelings and she is revealed to be the reason why he decides to return Konoha in the novel Sasuke Shinden: Book of Sunrise.
- Sasuke's Japanese voice actor, Noriaki Sugiyama, joked that Sasuke is "fearful" of Sakura due to her temper and how she acts like the boss in their relationship and marriage.
- Sugiyama hinted that Sasuke realized he loved Sakura romantically and they had a bond that went deeper to the point it was unbreakable after his final battle against Naruto in chapter 699.
- It is stated by Kishimoto that Sasuke is very pure when it comes to a girl, though he still gets embarrassed by it. Despite that, he is very straight forward about his feelings. It is also said later on that Sasuke is the type of person to never engage in close or intimate moments with a girl unless he loved her, which is why he never did so until he started reciprocating Sakura's feelings.
- While Sakura devoted herself whole-heartedly to loving and saving Sasuke and forgives him for his past actions, Sasuke actually feels guilty for the pain he put her through and wants to repay her for how much she's given him, especially following the birth of their daughter and giving him a new family.