There are tons of guns in this novel, and where you find tons of guns, you usually find lots of death. Postapocalyptic Chicago feels like a warzone at times, and death comes with the territory disputes.
Tris carries a lot of death around with her. Both of her parents died in a blaze of sacrificial glory at the end of the last novel, and Tris herself has killed a man, albeit in self-defense. She has to cope with all these deaths and try to come to terms with her own inevitable demise over the course of Insurgent.
Questions About Mortality
Do you think Tris is brave or suicidal?
Why does Tris want to die? What makes her change her mind?
How do the Dauntless view death? Does this explain Tris's behavior?
Why does it take so long for Tris to get over shooting Will? Do you think Tobias feels similar about shooting Eric?
Chew on This
Tris has an easier time accepting her own death because her parents died with a purpose (also because she is both Abnegation and Dauntless). If she can give her own death a purpose, she has no problem with dying.
Tris is also Erudite, which causes her to think of death in a logical manner. Her conclusion: it's not logical for her to die. Yet.