1) ...go there? Fantasy, especially amateur fantasy, is full of characters who really have no business, and no compelling reason, to go hieing to whatever the local equivalent of Mordor is. They hear a rumor, think it would be a good idea, get persuaded by someone else using logic that wouldn't convince a flea to jump off a dog, and go running off, tearing through the story's logic and consistency as they move.
Before you have your characters dash away in some random direction because the plot requires it, think. Is going to this place really that good an idea, judged on the risks they're taking? If they know that they would risk their lives passing one town, and would be able to pass another without trouble, why in the world are they passing near the dangerous one? "Because the book needs an action scene" is not a reason. Nor is "the heroine thinks her long-lost brother might be there, so she's trying to find him." At the very least have them sneak in, not go marching in as if they won't be recognized and seized and thrown in jail.
To find an example from a good book of what really happens when insane batshit antics start up in the fantasy hinterlands, read Terry Pratchett's Monstrous Regiment. One of the most vivid scenes in there is of the heroine, who's disguised as a man to get into the army and find her missing brother (whom she needs so that she can keep the family inn), marching with her regiment towards the front lines. Families, farmers, and animals are heading past them- in the opposite direction. Sane people are not going to want to wander around in the middle of a war zone. If you're sending a character there, it should be something like Polly's quest, not just, "I wonder what's over here?"
2) ...do that? There are obviously numerous examples in fantasy of this, and I couldn't tackle them all. But I'll divide them up into two big subcategories: stupid heroes' actions and stupid villains' actions.
Once again, stupid heroes seem to forget that they're often at peril of their lives, or at least at peril of capture and loss of their secrets and whatever powerful treasures they have. They draw attention to themselves by swaggering around a city, probably healing people and interfering openly in whatever activities they find heinous. And of course it works out, because the author can't bear for them to suffer when their intentions are good. Force heroes to choose more often between their quests and saving some random person, I say. And don't make the random person the key to the quest all the time, either.
Stupid villains annoy me even more. The author wants me to believe that this person is clever when they hire "elite" guards the hero can easily defeat? Or when they send servants of slowly increasing strength, instead of using their strongest weapon immediately to destroy someone who could be an incredible threat? Sure. Again, unless your villain is a cackling madman (and those are overdone), don't have him pull stupid shit like this. Ask yourself what someone sane would do when they have the villain's priorities. If he wants to prepare his armies quietly, is he really going to have them running around and burning random villages before he's ready to march? If he needs the help of a certain politically powerful noble, would he really intentionally alienate the man by showing him things he'd find repulsive, or poison him just because he was bored?
Capricious characters can be fun, but if they violate their own supposedly dear goals, the fun stops.
3) ...trust that person? It's unfortunate, really, that some fantasy authors even try to maintain a sense of mystery. They're just not any good at it. From the moment they put a traitor in the story, it's usually obvious who it is- often because the
Yet everyone else in the story trusts him. And the
Repeat after me: Do not violate sanity for the sake of the plot.
If there's "obviously" a problem with this character, the others should have strong reasons for continuing to trust him. Someone they just picked up on the road shouldn't win their instant affection and support, especially if the one doubting him has been a member of the party in good standing for years. And the teenager's insight, if it's in the story for a good reason (not that it is, 99% of the time) should be allowed to function, not abused. Giving a character important and Obviously-Very-Right revelations and then not having her share them because her fear of being embarrassed is stronger than her concern for the entire party's lives is a moronic way of manufacturing Diet Coke angst and an "I told you" scene for the cowardly, non-intuition-sharing character.
Here, have another quote from LeGuin: "No one who says "I told you so" has ever been, or will ever be, a hero."
4) ...put up with this? I don't care how saintly a person is, or how long she's been waiting for the coming of the True Destined Hero. When she's stuck in the rain, which has been falling all day, and can't find the secret entrance to the underground passage, and the teenager behind her is whining about how much he misses his mommy, I would expect some reaction. If she doesn't turn around and slap him, at least have her roll her eyes and continue sarcastic commentary in her head.
I've read plenty of fantasies where ONLY ONE character is allowed to angst, and that's the designated Author's Darling. Everything bad that happens, no matter how small, is excuse for complaining and moaning and whining and (to paraphrase one line of David Eddings I actually like) bringing up the grievance again like stale vomit. She screams and stamps her feet and does things that would be irritating in any normal context, not to mention the dangerous ones that fantasy usually takes place in, and is only coddled and comforted and soothed. No one ever, ever beats her around the head or tells her to shut up or hacks her arm off with a chainsaw. (Except me, in my imagination. And that's not nearly as satisfying, since the other characters are still putting up with it).
The same thing applies to other trivial actions. For some reason, the idea that the heroine should be able to buy the perfect dress takes precedence over buying, say, food for the humans and fodder for the horses, at least judging by how much description most fantasy authors give one as opposed to the other. And the other characters nod and grin, and no one blames the stupid bitch if the bad guys catch sight of her across the market while she's fingering fabrics. She needs her pretty dresses, after all!
Another variation of this is keeping some trinket or marker that the bad guys could recognize her by very prominently displayed. For some reason, all those heroines with mystical markings on their faces never ever think of using makeup to conceal them.
And everyone else in the story nods and grins along.
They are loons. They have to be. It's better than thinking the author is.
5) ...feel this way? I'm thinking of all the heroines who get incredibly upset whenever someone tells them they look nice, as if all of them have a stick up their compliment-taking orifice. I'm thinking of the people who watch their entire family die, shriek "NO NO NO," and on the next page are cheerfully contemplating their possible family-free futures. I'm talking about the characters who swear blind in the first chapter that they're afraid of something- the dark, the sea, the Dark Lord, the seesaw, whatever- and then three chapters later are "cheerfully accepting" that they have to go underground, or go sailing, or go to the Blasted Lands, or whatever.
People, people, people. Consider what reaction is appropriate to the plot, by all means, but also consider what reaction is appropriate to the situation as it looks to an outside reader who does not share your compelling interest in that plot, not yet- or can be jolted out of it as fast as breathing. If the heroine has a real problem with compliments, this needs to be explained at some point. Also, if she has a consistent problem with compliments, she should not snap at the older man who compliments her and just blush and mutter "thanks" at her teenage love interest. The plot taking over from sanity again.
Similarly, if a character has gone through a life-changing event or has a life-affecting fear, don't toss those out the window when they're no longer convenient. This is why dropping things into the book like "Queenie likes to garden" or "Gadge is afraid of small dogs" is not characterization. Too often, the author forgets it and moves on to something else, and it never does get integrated with the rest of the character's emotional scenery, lying there like the unused plot device it is.
In some fantasies, the only way to explain most people's behavior is that the local asylum birthday bash let out early. And it shouldn't be that way.