As a result of the dark night of the soul in my book Disciple, my main characters spend some time wallowing in despair. One of them is presented with the opportunity to do a Face Heel Turn (caution: TV Tropes link. There will be more of these.) and that required some thinking.
When I wrote the first draft of Disciple, Part V, I spent some time on TVTropes.org looking at the many tropes involved in the dark night of the soul and recovery from it. Each of my three characters went into this part of the story with different motivations, reacted differently, and came out on different trajectories.
Very much like a slingshot maneuver across the dark side of a planet: when did they fire the engines, at what angle, how close to the atmosphere (danger!) did they skim -- ONOES, sci-fi metaphors applied to fantasy!
I classified this particular character's quandry as a Despair Event Horizon approach because of an Et Tu, Brute moment. Plus, the Corrupter makes An Offer You Can't Refuse. I also calculated this character's likelihood of turning with TVTropes' Sorting Algorithm (the instructions there are wrong: according to their examples, pick a score for each row, total and divide by the number of applicable rows.) This character scored a 3.1, pretty much dead center on "Who Knows?"
All of which helped clarify my thinking but ultimately left the answer up in the air. It's a question of character, after all, not a mathematical formula. My gut knew what it wanted to do -- this was all set-up for the big climax in Part VI -- but my brain demanded that we do this right. Set the patterns so they would remain consistent, keep the challenges real and serious, do nothing accidentally.
To tie this in with my upcoming book release, the character patterns involved hearken all the way back to Disciple, Part II.
Do you use TVTropes.org in your story planning? Not just getting lost in the site -- we've all done that -- but really used it? I've mapped out parts of Disciple in terms of their tropes, but doing the whole thing would be a butt-load of work. I've found some interesting insights, and the site does tend to drive home that there's "no new thing under the sun" when it comes to stories. It can leave you questioning your originality. Or you can see it as a near-infinite list of ingredients you can cook up a story from.