Sasuke. Naruto’s closest friend and rival evolved majorly during the whole timeline of the series. His evolution definitely owed it to the complexity of his character, his struggles, and his past.
Awakes his Sharingan completely
Sasuke has a special kekkei Genkai technique, the Sharingan because he is part of the Uchiha clan. Before the beginning of the series, Sasuke awakened his Sharingan unintentionally during his family’s massacre but never knew how to use it again. It was when he was battling Haku that he obtained control over his technique. Later, his Mangekyo Sharingan appeared again when he witnessed his brother’s death.
Sasuke changed his weapon of choice after fleeing the village. He chose to wield a sword, the Sword of Kusanagi, and combined his lightning techniques with it.
Found out Itachi’s truth
Sasuke always thought that Itachi was evil and killed their family with ill intentions. However, after his final battle with his brother, Sasuke finally learns that Itachi was conflicted with an ultimatum by the village’s leadership. Everything Itachi did was to save the homeland and protect Sasuke himself.
Obtained the Rinnegan
Sasuke also had the blessing of the Rinnegan, even rarer than the Sharingan, by the Sage of Six Paths. This made Sasuke one of the strongest ninjas, with so many powers and techniques up his sleeve.
Even though Sasuke’s life was driven by vengeance and he was always ready to kill anyone, he soon gained friends like Naruto and Sakura. He realizes that he can become powerful with friends by his side, rather than bitter with spite and sorrow,
Becomes a hero
Sasuke was the biggest threat to the village. However, after uncovering his brother’s truth, he decides to save the ninja world, not destroy it. He grows into a hero and with Naruto and Sakura, he ends the war.
Starts a family
Sasuke was always haunted by memories of the loss of his family. This always bothered him. After the war, however, he returns to the girl who always loved him – Sakura. He settles down with her, marries and has a child, Sarada. He is surrounded by love and care, urging him to rebuild the Uchiha clan.