At the end of chapter 9, what does Ender do differently when he comes to the snake at the End of the World in the mind game? What happens?

Ender returns to the game and enters the castle room at the End of the World. This time he kisses the snake on the mouth instead of killing it. It turns into Valentine, and when they touch the mirror together, the wall parts and allows them through. He thinks that "wherever he went in this world, Valentine was with him." He is distressed that the snake was Valentine all along while he kept killing it.