Sasuke’s Training
While Naruto was undergoing his own special training in order to accomplish his goals, Sasuke was trying to increase his power. Unlike the series protagonist, however, Sasuke was willing to use dark means to do so. This meant turning to Orochimaru.
Orochimaru is a member of the legendary Sannin (as is Jiraiya), and a former member of the Akatsuki. He wants nothing more than to find the secret to everlasting life, and is often intrigued by powerful shinobi. This leads him to want to learn from them and add them to his collection.
He helps Sasuke tap into his inner power while also trying to warp his mind so he can use him and eventually murder him. Sasuke gets the drop on Lord Orochimaru though, killing him. His training then takes him to more unsavory teachers. Joining the Akatsuki puts him in contact with Madara who promises to show him the Uchiha’s place in the world.
Sasuke is a lot smarter than he lets on, though, using each opportunity as a stepping stone for him to find his own understanding of the world and the events that helped mold him.