Actually, Cayal, you could do what I've done with my so-called "evil" characters and make them seem evil, but when one digs deeper, they're merely insane. But a character (or reader) would have to dig VERY deep to figure that out. (As in, to figure out that said "evil" character could actually be diagnosed with a mental disorder of some sort.) Good and evil are actually relative-it often comes down to a matter of opinion of ends justifying the means and intentions. And even those who perform acts that are generally universally recognized as evil at a glance, why, even that is relative. (And don't forget either, Cayal-characters can turn from good to evil and vice versa. Darth Vader is actually a prime example of such.)
Motivations, though.....in the general cliche of SF/F, it's that an evil character simply wants to "rule with world/galaxy/universe with an iron fist". Too cliche. Vengeance can be another cliche, but it can be a GOOD one. Vengeance is never corny, unlike powermongering can be. It's a believable, sympathetic stance, tried, but true.
And some might say, "But Karn.....what about YOUR opinion on evil for evil's sake? Others have expressed theirs!" My opinion on evil merely for evil's sake? It can be very tricky to pull it off in a flavorful way. Cold, calculating, chaosmongering characters (Try saying THAT ten times!
) can often be very dark, very scary, and draw a reader in-or so laughably cheesy that you'd leave the book to a mouse. (And no offense to yesterday's birthday girl with that username.) Evil for evil's sake.....try to steer clear unless you know what you're doing.
There are other motivations, but I'm simply too tired tonight to list them. The ones I personally stick to are vengeance (Both truly justified and not) and upsets from mental disorders (which can possibly excuse a character's personality, but not their actions). But the human imagination is as vast as the endless universe itself, and new ideas spring to mind every minute. It's ultimately up to you to decide what drives your characters, but don't write them in a way that they won't ever capture your readers. Characters are, in many ways, (actually in most) the most important aspect of a story. They drive the plot, they have their individual quirks and personalities that a reader can get in tune with, or speculate on, or even shake their heads at in disgust or awe as they devour your words. But characters NEED characterization, and if you're not satisfied with something, then change it. All decisions are, ultimately, yours, and your imagination is your imagination. Also attempt to write the backstory of your world and write in your environment before you start tackling characters. And also, even in fantasy, do not rule out medical advances of sorts, especially in that of diagnostics. It can add quite a quirk to one's world that can explain a character's actions well enough to make them believable, and yet possibly be just obscure enough to stir primal instinct emotions in the reader that forces such an audience to continue through the pages. Thoughts such as, "Oh, he's a dark lord, and he wants taxes and slaves" tends to be a yawner for most people these days, and yet they are still the most common form of ultimate evil character. People are starting to ask, "WHY are they like this, though? Their motivation for performing evil deeds is to gain ultimate power, but WHY do they want that power? Especially if they already have so much power they don't truly need it?" It's at times like that that a given mental disorder can answer those questions, and give the character their own......unique aspect that others don't share, give the audience something fresh and new.
