(Note: this post will be packed full of Divergent and Insurgent and surprisingly, Harry Potter, spoilers, so don't read it if you don't want to be spoiled!)
(Also, there is no reason to infer anything about book 3 from this post. Just responding to a bunch of questions that have popped up in my tumblr ask box recently. To quote Conan O'Brien: keep cool, my babies.)
(source) Many people ask me variations of this question:why did soandso have to die? A couple times I've also been asked: Why don't you just kill minor characters or ones we're not attached to?
Let me address that last one right away: I think it's a good thing that the characters I "kill" are ones we're all attached to, so that those deaths are not gratuitous. Why? Because I don't want the books to be like Grand Theft Auto, where people get killed all the time but no one really cares or thinks about it. (That game can be fun, by the way, but it just wouldn't make a thoughtful book!) Even though I write violent books, I don't want to make people desensitized to violence, ever. That means that when someone dies, I want to feel it, and I want you to, too.
(Whether I have succeeded in that goal, by the way, is up for the readers to decide. But I'm just talking about what I try to do, not what I do perfectly!)
But my real philosophy of character death in the Divergent series is that the world Tris lives in is supposed to be messed up. And there's a war going on. And from all I've ever learned about war, if you're involved in one, people you care about will be killed, and it won't make any sense to you, and it won't be fair, and it will be at all the wrong times, and some people will lose more than other people, and that's just how it is.
It would be far too convenient for Tris to retain all her friends and family while all these other people are losing theirs. Especially since Tris's friends and family choose to directly involve themselves, perhaps more than others, in violent and difficult situations. I try to be just as unfair as the world is; I take away characters when I have to, and I don't really think about whether it's balanced. Tris loses both parents; Tobias and Christina lose neither. Tris gets to keep her boyfriend; Christina's is taken from her. It's not fair either way, and that feels honest to me.
I think I learned this lesson from Harry Potter. Would we would really, truly have believed that Voldemort was a heinous villain if no one Harry loved had died? Would we have believed that his world was being pitched into darkness? Would his sacrifice, in book 7, have felt truly necessary to us? I really don't think so. I was very attached to the characters that died. I remember crying like a baby in my bathroom before school when I read book six. (Big mistake, reading the end of that one before school. Seriously.) But their deaths made Harry's world, and the state it was in, so much more real to me; they made his search for the horcruxes and his defeat of Voldemort feel so much more urgent. Those books wouldn't have been the same without Rowling's willingness to make sacrifices. That, more than anything, made me decide that if I was going to be an author, I had to be willing to make sacrifices too.
As for why certain characters over others, well, I don't know. I think people-- even writers themselves!-- sometimes have the impression that the authors of stories are completely in control of those stories and the characters that inhabit them. That really isn't true for me, though. I know it sounds crazy, but I create the characters and they become real to me and then they do whatever the heck they want. (Especially Peter. Whoa.) And when characters die, it's usually because I hit a point in the story where I don't feel any danger anymore, because no one Tris cares about is in peril, and then someone goes. BAM. Who that is depends on the moment in the story. It's often a shock to me.
In any case, what I'm saying is: I don't have that much control, and I try to follow each character's nature. (IE: the Abnegation will be more likely to die because they have that impulse to throw themselves in front of others. The Dauntless are more likely to die because of unnecessary heroics and recklessness. Etc.) I also try to be real with myself about what kind of world Tris lives in. She is not immune to its corruption or its violence. (And frankly, I think it already requires some suspension of disbelief that she didn't die in Insurgent.) All that I can do is try to have her react to her losses as realistically as possible, which often means that she's unlikable, as grieving and guilt-ridden people sometimes are.
So, that is my Official Writer Philosophy of Character Death.
In other news, will I ever be able to write a blog post without referring to Harry Potter? I'm not sure.