More on motivations;

One of my projects turned into a muddle because I didn't give one character ANY motivations. I gave him a lot of actions and an interesting background, but only hints as to motivations because I hadn't thought his motivations out. He ran around, he gave hints, but... no reasons.

That stunk.

There's a fine line of balance. In RL, you never know a person's true motivations. The difference between reality and fiction is that fiction has to be beleivable. (to paraphrase Twain)

Let's take X-Files as an example, shall we. Mulder was driven by his sister. That memory haunted him. He wanted to explore the absurd, to find the unreal, because of it. It was a comic book motivations. "My... sister... dissappeared... when... I ... was... young!" It was kind of a big deal.

...what was Scully's motivations?

They were a lot more complex. She was driven by a desire to succeed in her career, a logical skepticism, and even by loyalty to Mulder. Yet she continued doing the job, going above and beyond, time after time after time. We saw glimpses of reasons. We saw some braveness. We saw some real fear. We saw, above all else, an almost real person.

Almost real. Nobody's quite real in fiction.