Motivations are something I'm still trying to lock down. Why are specific people doing certain things.
Some folks just do stuff that's expected of them. In NERO, for example, not a lot needs to be put into motivating people. Players are there for a weekend, and if the leaders of the town say, "We're fighting goblins today!" everybody packs up their stuff and goes to fight goblins. While there's a lot more complexity than that, at the basic level, adventurers do things because they're adventurers. They're in it for the excitement and the money, and because somebody needs to fend off the Big Bad.
Unfortunately, what I'm working on is
less clear-cut than that. There's internal politics going on, and there's two characters where I really need to hammer out their motivations. Since I don't want to make it a clear Good vs Evil issue, it's not going to be blatant - I can't have these two characters just walk in on the Other Guys sacrificing a kid or something.
If people are part of something, and there's some sort of falling out, they typically just turn away from it - people leave relationships and move on, people leave churches, etc. But it takes more for them to go a full 180, to shift from "part of group X" to "no longer part of group X" to "part of group Y which is actively opposed to group X". Something of that magnitude, where you're willing to take up arms against former comrades, that's severe. Taking out the massive, heavy-handed bitch-slap ("I never knew that the Order of Goodness sacrificed puppies to the Forces of Evil, I must stop them!") means getting personal.
Now, personal can still be heavy-handed. In some of the Star Wars series, there's a fellow named Kyle Katarn - a dude who went to the Imperial Academy and was trained as a storm trooper (and swallowed the typical Imperial propaganda)... until the Imperials killed his father (a Rebel sympathizer) and tried to pin it on the Rebels. Once he figured it out, well, then, the evil of the Empire was duly exposed, and our Morally Upright Protagonist was obligated to switch sides and shoot them Evil Imperials. Toss in many dead Bothans, and the Death Star plans end up getting to Leia. Hurray, Good Guys Win.
But I'm trying to avoid that, because the real world is never that black and white, never that clean. Sure, the British did horrible things in Northern Ireland (for instance), but the IRA inflicted some horrible casualties as well. Both sides have innocent blood on their hands, and both sides feel entirely justified in what they did. (Or, at least, did at the time.)
Which highlights the usefulness of religion as a motivator. Different religions means that there's the possibility of religious war, and that's a time-honored story. Crusaders, taking up arms to free the Holy Land... and doing despicable things along the way, both to their enemies and to innocent civilians.
But I'm not sure I want to entangle religion into the story quite in that manner. There's going to be religion - but the dominant religion has some pretty hard-to-deny proof (effectively, miracles on demand) which makes it harder to argue. While there might be some stragglers, I don't think that they'd be large enough to pose a credible threat, nor am I certain that the two characters I'm thinking of would make that sort of swap.
One of the characters, I've got a possible reason (assuming I can work out the details to make it work/be internally consistent), and while it borders on the heavy-handed, he actually really did deserve what he got, so if I can get the details in line, he's okay.
But the other character is more of an enigma to me right now. I could use something similar to the first character's motivations - but I don't want to beat a dead horse, and it might change the balance I'm working on establishing. Unfortunately, this is one of the main characters, not a secondary, so he's far more complex, and needs to be well-thought-out.
Back to the drawing board. (Or, well, in my case, the over-sized dry-erase board in my office.)