Chapter 26 of Divergent by Veronica Roth

I find the most important line in a chapter is often the last line in the chapter. Authors frequently foreshadow what will happen next and give the perspective of a character as it relates to what happened in that chapter specifically. On page 301, the last line of chapter 26 is "It will never happen again." Let me explain what has happened in this chapter to make this line important.

Tris is staying in the Abnegation headquarters. A simulation has arose and some people have been influenced to do things they wouldn't have done otherwise if they were not under the simulation. Specifically, Al (one of Tris's friends) has died. I believe this angers Tris to say that it will never happen again because she is angry that yet another person has died because of the simulations. This also foreshadows in the later chapters that she may attempt to stop this from happening again. It shows her anger and passion toward the Erudite, and perhaps motivation to thwart the next attack.