I asked in the past if imagining ideas for a story was OK, and you said that you couldn't see anything biblically wrong with it. But I feel like I need some details.
For example, I heard of some Christians (not that I judge their opinions or anything) saying that they should ban "Harry Potter" because it was about wizardry and magic. I don't agree with this, but I guess I don't really pay attention to it. But as I think about it more, what I like to imagine is also kind of like "Harry Potter," although less about the magic. I just love ideas that are fantasy related, about knights, dragons, olden days, history, and even wizards to some degrees. I wonder what the Bible says about that. Also, the stories usually include some violence like wars and battles between armies, but the stories aren't centered on these ideas. I was wondering if it presents a problem.
Recently I stumbled on your web site a topic about Grand Thief Auto and how it was not an ideal game for Christians because of its adult content. I don't know. This didn't really bother my conscience before.
I have found in the past that people who objected to the Harry Potter series did not do so from a moral stance. Oh, they claimed that they objected to the references to witchcraft in the story, but when I asked them about the Chronicles of Narnia which also have magic and witchcraft, they could not tell me why the Chronicles of Narnia were acceptable and Harry Potter was not. There are also J. R. R. Tolkiens books which have magic and warfare described in detail. Where are the protests against these books? Curious and digging further, I finally concluded that the root cause was envy at Rowling's success.
I happen to like fantasy stories and the reason is straight forward. Because the author has to make up a world, more effort is put into describing the environment. The result is a story with richer details. Because the situation takes place in a different culture, I rarely find profanity in these stories. Unfortunately these authors still feel the pressure to put in scenes featuring fornication at times, but strangely enough, it is almost always milder and less "in your face" than the fiction written in a modern setting. I also enjoy detecting and watching how an author's religious beliefs intertwine in the actions of his characters.
For some reason, writers of modern fiction think that in order to make a story realistic you have to include all the base elements of the world. Some times I wonder if they throw in so much sex because they really don't have much of a story and this the only thing which gets them readership. I have found a few exceptions. Richard Paul Evans manages to create wonderful stories set in the modern world which mostly avoids the trash of the world.
Older fiction is generally safer because the authors had moral standards and wrote about people upholding moral standards. Rudyard Kipling wrote both great fiction and fantasy in the form of children's stories. Charles Dickens is another that I have enjoyed. In neither one will you find them using sex or shocking language as a prop to hold up a flimsy story.
If writing about wars was wrong, then we would have to toss out most of history. Even sections of the Bible describe warfare. The question ought not to be whether war is described, but why is it being portrayed. Is it just filler, or is it serving a purpose? Tolkien, for example, used it to illustrate the battle between good and evil, while at the same time making sure the reader understood the horror of war -- he didn't make it seem glamorous but a hard necessity. C. S. Lewis did much the same, though he glossed over many details because he was aiming at a younger audience.
If you look in the Bible, you will find that sinful actions are described. Some are stomach-churning. But the thing to remember is that what is being described is depicted as evil and we are shown the consequences of that evil. Too many authors will write about sinful things and glorify it or try to convince the reader that good results from doing evil.
Whether we are discussing a completely made-up story, one that is recording history as it happens, or something in between, we need to realize that stories influence people. They are a form of instruction as well as entertainment. There ought to be a purpose to the telling of the story and that purpose ought to make people better for having read it.
"Let no corrupt word proceed out of your mouth, but what is good for necessary edification, that it may impart grace to the hearers" (Ephesians 4:29).