Okay, before you get after me, let me make myself clear. By 'abusive authors' I don't mean those authors who are always having their characters get beat up, tortured, wounded etc. Yeah, I would be calling the kettle black, but hey, I write adventure and realistic historical fiction. It has to happen, and you have to put your character in peril so that the reader will be scared they might not make it.
No, I mean authors who bend characters into someone they are not. Sometimes it really feels malicious to me. It's like they have their poor characters chained in their attic and they torture them until they promise to be who the author wants and not who they really are. Beaten, abused characters. It makes me want to give them a hug just like a little homeless puppy. And I'm not naming names for authors I think are guilty of character abuse, because I still have my honor as an author myself, but it does exist, my fellow readers and writers. Have you ever been in love with a series of books and then one just seemed very off-color? Or something happens that you did not in a MILLION YEARS see coming? Most likely it's because of character abuse.
As an author, let me tell you how hard it is to shape a character. They really have a mind of their own, and you would have to torture them before they would bend to your will. The best way to get your characters to have their own character is let them come to you, don't force them to your will. Trust me, they will be there for you eventually, it might just take some longer than others.
I always think it's terribly sad to see characters you know would be good people, or do more if only their author let them. Chances are, if you are trying too hard to write your characters, then you need to step back and wait for your characters to come to you. Here are some ways to avoid being an abusive author:
Pick up one of your favorite books with a character you really love in it. Read your favorite parts and ask yourself why you love it so much. If it's a series, think about how the character has changed over the series. Not all series characters change, some characters are static like Sherlock Holmes. Other characters do change due to events that shape their lives. But are these changes for the best, or do they seem random and out of the blue. It can work backwards the same way too. If a character has gone through a traumatic event at the end of one book and are totally fine in the next one, this can be out of character as well. With your own characters, try to put yourself into their shoes. If you were your character, judging from what you know about them, how would you react to the situation they are in?
If you don't know your character well enough yet, or are new to writing in general, try some free writing and put your character in different situations. Don't overthink what they would do, but let the story and dialogue flow. If it still doesn't seem right, try several different times. I know for myself, especially in my older writing, I would write random scenes from my stories before I would complete the book, but a lot of times I would either end up discarding or majorly changing the scene to fit the characters better once I know them on a more personal level.
Just like with your friends and acquaintances, you will get to know your characters better and better the more time you spend with them. This is one reason why I don't suggest anyone plunging into a book without a little forethought of the matter. The concept of 'writer's block' is really a lack of direction and indecision within a story. Chances are, if you are experiencing the dreaded 'writer's block' you are lacking one of both of these: A story direction, or Character Familiarity. With your friends, you know them pretty well, especially if you have known them for a long time. People change with age, characters can too, they are human after all! But these are minor changes that naturally happen. If you are planning on a big change then there needs to be a darn good reason for it. Nothing less than the loss of a loved one, or some other traumatic experience. And usually, the problems this causes the character should be resolved at some point, or at least put in a position to where your character can deal with them. Your character can't just go randomly postal because the store didn't have his favorite pop-tart flavor. Not unless, A. that is his character, or B. it is the result of something bigger in his life.
A bit of a note on Villains: Some villains can turn good, BUT it cannot happen out of the blue and without good reason. To set up a story line where a villain will turn good in the end, you'll want to make sure they have a sympathetic backstory that the reader can identify with. You can also not make the villain you want to turn good a disgraceful nasty person no one cares about. If you do, you'll only make readers mad if you turn him/her good in the end. As a reader, I am going to say upfront that if there's a terribly nasty villain, I want to see him/her get theirs in a satisfying way. Baddies who can turn good though, should have morals. Sure, they can want to kill the hero, they can even torture him and his friends, but you should probably steer clear of his killing women and children (unless it's a terrible accident which could actually lead to his turning good) or doing other nasty unforgivable things.
So, please my fellow writers, don't be an abusive author, let your characters live the lives they were meant to!