The shift began after Naruto defeated his own inner darkness at the Falls of Truth. During his battle to control the Nine-Tails’ chakra, Naruto met his mother, Kushina Uzumaki, and learned the truth about the fox’s history.
Kurama, seeing Naruto on his knees, mocked him. "You are weak," the Fox sneered. "Give me your soul, and I will save you."
The true breakthrough happened during the fight against Obito Uchiha and the other Tailed Beasts. Kurama watched as Naruto fought to protect the other Jinchuriki, noticing that Naruto didn't want to control them—he wanted to save them. The Breakthrough Steps: