I tend to avoid books if I know beforehand that major characters will be killed off. I like to be uplifted, to lose myself in a world away from this world where people triumph against adversary or personal struggles and make it out on top. And alive. I want to cheer them on and to be reminded that no matter how hard or dark life can get, anything is possible. Things will be okay. Magical unicorns and wish-granting fairies do exist.
And when that character I've grown attached to and rooted for since the beginning dies at the end of the book or series, it can be pretty devastating--so much so that it ruins everything for me (I'm looking at you, Mockingjay).
But lately I've found myself contemplating just that. Killing off important characters. Maybe I'm beginning to understand that things aren't always going to work out okay. In a world where bad things happen, death is part of reality. It doesn't have to be gratuitous. It can be purposeful, to drive a character's mental or emotional growth or to show the bleakness of circumstances. And it can raise the stakes, because no one is immune to death.
Understanding it doesn't make it any easier to do. Because killing off a character is just that: an end for the character. There is no more growth or development. No more adventure and discovery awaiting them. All of their goals and dreams before their deaths will never be achieved. They are wiped from existence and there is no taking that back (unless they are revived or evil twins take their place, as happens often in soap operas).
And maybe, at the core of it, I see my characters as real people, having delved deep into their minds and brought them into fruition. It's hard to extinguish that without losing a piece of myself.
So I guess, to sum up everything, what I'm trying to say is that I'm a big softie.