What sort of stuff do you do to your characters?
Do you torture your characters? Do you pull the rug out just when they are about to make some progress? When they're celebrating some small victory, do you visit disaster upon them? You should.
As you know, I'm a pantser. I write by the seat of my pants, the characters tell the story to me and I write it down. That is not to say I don't have input. I do, for I am their god. I don't think they realize that, probably a good thing. Better to be a secret god. That way I don't have to be bothered with their whiny prayers and righteous indignation. I won't be asked, "How can you let this happen? Or, "Haven't I always believed in you? No, no, better they don't know about me because I am a sneaky, rotten, no-good s.o.b. I don't want to have to answer for that.
I once, just when my protagonist amassed enough men and weapons to pose a serious threat to my poor little disturbed, misunderstood, antagonist, I whispered in her ear, "Time to ride the dragon." She did, discovered the army and wiped out three quarters of them. I could only shake my head. "Egon, Egon, Egon, why was no one watching for Katerina and her dragon?" It's sad, but some lessons are really, really hard.
Lest you think I only do bad things to protagonists, I let an arrow shot by Egon part the collar holding the charm that allowed Katerina to control the dragon. That is a horrible sentence but I'm letting it stand to underscore the importance of reading your work out loud. Give it a try. Now I can hear you thinking, 'Egon shot the arrow. This lunatic with the god complex didn't do anything.'
That's exactly the point; I didn't do anything, I allowed it to happen. I could have summoned a gust of wind to blow it off course. But, I let catastrophe befall poor Katerina. She had to leap from the angry dragon, turn herself into a crow to save herself and spend the night in the mud under a bush because she didn't know how to get airborne. More importantly, the dragon was lost to her.
Okay, I told you all that because, 'Do bad things to your characters to make your story more interesting.' would be a very short blog post. That's it in a nutshell though.You have to be evil for the sake of the story. You must make your characters suffer, sometimes die. In my first manuscript, I killed the title character two thirds of the way through. Albert actually killed him but it was because of my tinkering. Overcoming disaster, tragedy, insurmountable odds and well meaning idiots builds character in protagonists and antagonists alike. And that's what we're after; strong, interesting characters.
It's up to you, as their god, to forge them with pain, disappointment and sorrow. You control their world, use that: floods, earthquakes, meteors, a rolling boulder, a toppling tree. You can arrange circumstances to rouse their greatest fears, use that: a loose lion, a raging river, an unstable rope bridge over a chasm. You can foster misunderstanding, paranoia, and hate. You can make their lives a living hell, and you must. It's for their own good.
So, tell me some of the things you've done to your characters. Or, some of the favorites you've read.