Surprised by the Nine-Tailed’s chakra, Sasuke asks Naruto who he is. Naruto replies that he is a friend. Naruto attacks, and Sasuke can’t keep up with his speed. Naruto begins to hammer some common sense into him, causing Sasuke to scream that Naruto, who has never had a family, can’t understand what it’s like to lose them. Naruto admits that this is true, but says that he has come to think of Sasuke as a brother. Realizing that Naruto treats him with family ties, Sasuke’s Sharingan fully develops. He puts a protector on his forehead and promises to sever their bond so Naruto won’t pursue him again.