I did different perspectives as if they were introducing themselves

Tris: Hello my name is...Tris. I just transferred from Abnegation which is all about selflessness. We where ordinary clothes
with ordinary hairstyles and shoes. I came to Dauntless, which is all about bravery. I also have a brother named Caleb.

Caleb: Hi I'm Caleb, I transferred from Abnegation. My parents thought I was going to be the one who stays but I just felt...weird there.
If a child leaves thier old faction they can't go back and a parent can only visit once. I think something is stirring with Abnegation and Erudite (The smart)

Four: I'm Four. Four is my nickname, I've never told anyone my real name but some people know. I have the name Four for a reason. I transferred from another faction but I'm not telling anybody. I have multiple secrets but no one can get them out of me or at least I think so.

What are Four's secrets? What is the tension between the factions? Why did Tris transfer? Read the book to find out.