Sliding over from writing a book to creating characters for gaming purposes is a fairly simple endeavor, plus one you can steal ideas from to build upon your book. Yes, I said steal. Because nothing says creative like your DM telling you that your gnome just bought a time share in Hell with a lovely view of the Lake of Fire. And why did your gnome do this?
“It seemed like a good bargain.”
Characters in gaming seem to never have to deal with the consequences of their actions. Kill off the local mayor because he was in cahoots with some dread underrealm godling and they move on, leaving the town to more or less pick up the pieces in the aftermath. The adventure party almost never has to deal with such trivial pursuits like “rebuilding” a town. But in books, it’s a far more compelling back story if the author keeps such incidences in mind.
How does a community, which had been ruled (unknowingly) by some evil and vile character, pick itself up after being “liberated”? Is there a massive power vacuum? Does the town crier take up the call to be mayor? Does the town (unwisely?) elect one of the heroes to become their new leader?
There is always a reaction to everything your heroes do. From a simple “No tipping the barwench” to “blowing up the Zerg Empire’s Space Station”, there is always some sort of reaction. Unless it is the culmination of the novel (or campaign), there is always fallout hat can be used in the novel. Tolkien did it. The best example, though, is what happened to Stargate: SG1 after they freed a bunch of worlds from the Go’auld.
An incredible power vacuum was created when the Stargate team rescued a planet from the evil aliens and then left. The people, most of whom lived as slaves, were left to fend for themselves. If advanced technology was available, the SG1 team took it. If the humans were “primitive”, then SG1 didn’t give them tech in return, because they felt obligated to leave them to their own natural directive. Eventually a bunch of said worlds banded together, created an alliance and declared war against Earth.
Sound unreasonable? It shouldn’t.
Star Trek: TNG did this too, once upon a time. They would preach about following the Prime Directive but whenever they came across new and exciting tech they would find a way to end up with it. There were many reactions to this later in the series (and subsequent series expanded on this), creating new allies and new enemies. It keeps the story fresh, casts the “hero” in a new light and the villain as a sympathetic being.
You sometimes want this. Really.