In the beginning of the book, the character Nick was still hung up on Tris and was unwilling to do anything fun or exciting. But when he met Norah, that all changed. Like when he offered to take Norah on an adventure around the city, taking her to the burlesque show and such. When he was with Norah, he didn't even think of Tris; only Norah. By the end of the book, he no longer cared about Tris, which is the exact opposite from the beginning of the book.

Done :)