Some know it as "Emotional Murder" or "Emotional Torture" Those responsible for this (directors, authors, ect.) are commonly known as... wait for it... Trolls.
That's right. Trolls.
So. Ready for a shock? It's perfectly fine (and I think better) to be a Troll of an author. The readers secretly enjoy it you know. No matter how much they wail and kick and scream about who you choose to kill off or maim or whatever you want, they actually LIKE the emotional torture. Why? People are just weird like that.
1) Make yourself do it.
Just because you're a "Troll" doesn't mean you don't have feelings too. These are after all YOUR characters. You imagined them, you came up with the name, you developed their story, and they became one of your favorites. You poured so much into that character and now... well you have to kill this character off.
The good news is since you did give so much to this character and since you made this character so likeable (or not so likeable) , your readers are going to love him/her. This means, as they like to put it, their hearts will shatter into a million pieces.
I have sadly been victim to this, so I know what I'm talking about. J.K Rowling went and killed my favorite character and when this person dies, I usually fall to pieces literally sobbing. It's not a pretty sight. My family knows not to come in or they might gets wads of tissue thrown at them. That's exactly the sort of reaction an author is wanting. (I know, it's terrible)
Foreshadowing is really, really tricky. You want to give the readers a particular feeling of unease, but you do not want to give away that certain plot twist. I'm always a little disappointed when I figure out the plot twist. I mean, it's nice to say "I KNEW IT" but really I prefer the element of shock.
There are ways of using foreshadowing to ones advantage however. They can be written so that they mislead the readers. You can totally make them think that they know what's going to happen and then... "Wait, what?!?!"
Make certain you have them squirming a bit as they wait for the next sentence. Their thought process should probably be along these lines;
"She wouldn't, I know she wouldn't. No one is that heartless. Wait... no, no, no! She wouldn't! She- OH SHE DID. WHAT A TROLL. OH THE FEEEEEEELSSSSSS"
Yes, I think that's how it should go. How does one do that you ask? Oh I'm glad you did, because I can give you my favorite answer...
If you haven't already guessed, I am quite fond of these things, and the more the better. One is not enough! I like to go by the guideline "Surprise your readers at least three times" and surprise yourself. Most of my plot twists weren't originally in the outline and they ended up shaping the entire story.
Make them totally unexpected (obviously) and keep them coming. Don't let your characters have to much of a respite or else the story gets boring.
Go with whatever comes to mind, because that's called instinct. If you suddenly get the urge to write something totally unexpected, do it.
So there you have it. Just a few tips on how to be a Troll of an author. Until next time!