I've written on this before, but I always hope I can improve on my explanation.
I like Darkness of the Soul stories, characters pushed to their bottom limits and still climbing out on top. Not horror, not necessarily suspense. Gore in print doesn't thrill me either, not like it does on the screen.
Often contrasting this, I dislike a great deal of internal narrative. To me it's often like a voiceover in film, telling what the story's about rather than showing it unfold. But how do you show Darkness of the Soul?
I've been watching Spartacus: Blood and Sand lately. It's oftentimes bad, and yet good, because it's gotten me thinking about character and plot structure. Spartacus is a Thracian slave turned gladiator. He doesn't want to be there, and no one else wants him either, but he won the crowd's favor with a great fight. He could give up and die. He's a gladiator slave in the ludis, after all, with no hope of freedom. He faces a future of only death and violence. And yet one thing drives him: seeing his enslaved wife found and safe. (I don't think it's the cleverest motivation, but it's better than him wanting to live just for the sake of living, and it's fairly noble, anyway, allowing our character to do horrible things and yet still keep us in his corner.)
Anyway, the effect is plain. Spartacus is enslaved, but not only to his Dominus. He's enslaved to his desire. And that gives the character strong motivation around which entire plots are built. Spartacus will do the craziest things, win the worst fights, and the audience believes it all, because of his motivation to save and protect his wife. He strikes a deal to fight and survive and make his Dominus a rich man, if only he'll find Spartacus' wife. The Dominus, incidentally, is absurdly in love with his own wife and has some pretty bad money troubles. Not a good man, but all that gives him some gray areas, and money and status motivates him to help Spartacus succeed. There are, incidentally, worse people on the show than Dominus.
Of course Spartacus fails in the arena almost immediately and is sent to the pits. This is cage fighting at its goriest. (As an aside, I wondered why they haven't managed to make the other episodes' blood effects look this good.) He is going to die there. It's only a matter of time. But while getting the living hell beaten out of him, he scrapes his way up to favorite there, too. He just can't give up, even when he wants to, because of his wife. If he dies, who will save her? Who will hold Dominus to his promise to find her? But the success in the pits frustrates Dominus, who hoped this would be a short term measure to earn some money off betting. His reputation starts to suffer, and he's not earning quite enough money to hold off the debtors.
So Spartacus finds a way to earn his Dominus more money and seal Dominus to the bargain of finding his wife. He swears to throw a fight and die, letting Dominus put all his money on the other guy, if he'll swear to the gods to find his wife.(Religion and the gods is another heavy motivator for all the characters, except Spartacus in this episode. He uses the Roman's beliefs against him.) Dominus, who loves his own wife, sees some nobility in that and agrees to the bargain. And when the fight comes along it doesn't look like Spartacus will actually have to throw the fight.
But then, one of Dominus' creditors send an assassin to kill him during the fight. So Spartacus kills his opponent and saves Dominus' life. He costs Dominus a lot of money, but Dominus now owes him a blood debt.
And that leads me to another point. In motivation driven story, there's no voice over required (or internal narration, etc). We understand Spartacus lives for his wife's safety, not because he ever says it, but because he remembers her by flashback, he talks to the other gladiators of it, and he's even willing to throw a fight to save her. Her safety resides in Dominus' vow to save her. So when Dominus is threatened, Spartacus saves him in order to save his wife. We also understand the two men are more tightly tied than ever.
The lesson here is clear. Use strong character motivation to drive your plot and story. That applies to all stories, not just Darkness of the Soul stories. Even though those are my favorites. :)