When he was a child, Sasuke was a very nice boy, affectionate towards his parents and his brother, and respectful towards his clan and his teachers.Sasuke it’s the friends of naruto in the first part of naruto. He was even very proud to be Itachi’s brother and Fugaku’s son. His initial dream was to join the Konoha Police Department later on, like his father. For this reason, he was very much looking for approval and recognition of his abilities by his father. After Itachi’s massacre of the clan, Sasuke’s innocence was damaged, his ideals and personality changed dramatically, he became cold, lonely, cruel, cynical, a little arrogant and for the next eight years of his life, he devoted himself to his revenge against Itachi.
When he joined Team Kakashi, Sasuke showed a great indifference towards his teammates. Feeling superior to them, including his master, Sasuke was not willing to cooperate with Naruto Uzumaki or Sakura Haruno, as he felt that they would not provide him with any help to kill Itachi. However, over time, as he spent more time with his team, Sasuke began to lose some of his anger, caring more about his team than his revenge. To help him regain his desire for power, Orochimaru gave Sasuke the Cursed Mark of Heaven during the Chûnin Exam to give him a taste of power. However, Kakashi sealed the seal and taught him the Thousand Birds in the hope of keeping him from the path of revenge and protecting his friends.
According to Kakashi, Sasuke has both a superiority and inferiority complex, as he is not willing to recognize when someone is stronger than him, but he is obsessed with the idea of someone being stronger than him. For example, he was complacent in his rivalry with Naruto, when he believed that he was stronger, but he noticed a rapid progress of Naruto, after his victory over the jinchûriki of Suna village, Gaara, who had already defeated Sasuke, and his quick defeat of Itachi, when Itachi returned to Konoha, Sasuke began to believe that his progress would be much too slow staying in Konoha, which led to his desertion to join the village of Oto to search for the power of Orochimaru. After deserting the village, Sasuke left with the Sound Quartet and went to the Land of Sound, only the members of the Sound Quartet had to fight against Sasuke’s search party and he had to face Naruto alone at the Valley of the End, where Naruto tried to save him from the path of revenge. Sasuke in turn intended to kill Naruto, his closest friend, to awaken his Mangekyo Sharingan, but despite his victory, he chose to go against his brother, and decided to defeat Itachi on his own.
In Part II, Sasuke’s personality returned much like it did in his first encounter with Team 7, as his revenge against Itachi was more important than anything else, including his own life. He also claimed that he had cut all ties with his life in Konoha, believing that they were the cause of his weakness, even going so far as to attempt to kill Naruto, whom he had spared in their previous fight, to prove how much he had detached himself from his previous life. Despite this, Sasuke didn’t seem willing to kill unnecessarily in his quest for revenge, and later when he fought the eight-tailed demon jinchurriki, Killer B, Sasuke was reminded of Team Kakashi as he saw members of his own Taka team sacrifice themselves to help him.
Although he had previously said that he didn’t care if he had to sacrifice his body to Orochimaru until he had completed his quest for revenge, when Sasuke felt that he had become stronger than Orochimaru, he declared that to surrender to someone weaker than himself was an insult to the Uchiwa clan. He started the battle and absorbed Orochimaru’s consciousness when Orochimaru tried to steal his body. This is just one example of the immense loyalty Sasuke has to his clan, bordering on obsession, he continued to wear his symbol on his back with pride, while he refused to wear any other symbols such as the headband. He also looked down on non-Uchiwa wielding the Sharingan, considering it an insult, that the eye is a symbol of the power of the Uchiwa clan, while Itachi and Madara praised Kakashi’s mastery of the Sharingan, more skilled than Obito Uchiwa, Sasuke expressed his resentment towards a non-Uchiwa for possessing it, and that Kakashi should be grateful to the Uchiwa for the power he had in his possession. Sasuke showed even more disgust when he saw Danzo with ten Sharingan in his arms, and an eleventh in place of his right eye.
After his fight with Itachi, which resulted in Itachi’s death, the revelation that he was ordered by the elders of Konoha to kill the Uchiwa clan coupled with the fact that Itachi really loved him, Sasuke vowed to destroy Konoha to the last inhabitant for sacrificing Itachi and the Uchiwa clan for their own happiness. The more Sasuke devoted himself to his new quest for revenge, the more cruel and ruthless he became. He also showed great rage whenever someone mentioned Itachi in a negative sense, crushing Danzo (who turned out to be a clone created by Izanagi) with his Susano for speaking ill of his brother.
Sasuke’s hatred which overwhelms him when he sacrifices Karin without mercy.
After Danzo’s death, Sasuke felt a joy of living that he had never felt before, and even after seeing the death of a high member of Konoha, it led him to the vow of wanting to kill everyone in the village to finally separate the Uchiwa clan’s ties with the village, and in doing so, purify the clan’s name. At this point, Sasuke’s hatred and thirst for revenge seemed to have crossed the point of no return, which Sakura (at first) and Kakashi concluded when they saw him, losing hope in a possible comeback on his part. Even Karin, despite being obsessed with him, gave up being with him. Now, the only people who still have some faith in him are Naruto, and lately Sakura, who decided to trust Naruto’s ability to save his friend and Sasuke’s ability to see reason. Sasuke, in response to Naruto’s relentlessness to save him, gave up his refusal to transplant Itachi’s eyes onto himself, hoping to gain his full power to destroy Naruto, hating him and what he stands for more than anything else for refusing to give up on delivering him from the grip of revenge.
During the Fourth Great Ninja War, Sasuke found Itachi and his hatred towards Konoha stronger than before, but at the same time, his brother’s willingness to protect his village disturbed him to the point of reflecting on his hatred. After hearing the story of the creation of the village by the First Hokage and his vision of the ninja, Sasuke decided to oppose Madara, to protect his village and to change the ninja system but his intentions remained unclear.
As far as women are concerned, he is considered as very handsome and cool by them. Nevertheless, he doesn’t show any interest to them. Only his relationship with his teammate, Sakura, was ambiguous. When he left the village, he addressed her a « Thank you » which can suggest different interpretations. The author delivers, moreover, in his Second Databook, that Sakura was the only one who filled his life with loneliness, but that he could not let her in because of his quest for revenge. In the end, he did not respond to her declaration of love for him.
Despite his deep ties to his team members and his attachment to his home village, Sasuke could not turn his back on his quest for revenge. He tried to break any link that he considered as a brake to his hatred, even if it meant trying to kill the people who were dear to him.