I don't like writing characters that fight against a super-bad-take-over-the-world-antagonist. I prefer when the plot is pushed forward by a character fighting against their own dark nature. I think everyone can relate to stories like that on varying levels.
So here's an example of what I mean when I say 'I write dark characters'.
I'm doing re-writes on a story where two brothers are the main characters. The older brother is 15 years old and is totally obsessed with keeping his younger brother safe. In his mind, everyone else in the world is expendable, including himself. Out of desperation, guilt and *duty*, he lets another character beat him repeatedly, he will fight, lie, betray and nearly kill to protect his brother. At the beginning of the story he is already in a bad place, but as the story progresses he is slowly driven into a corner until he's nearly sociopathic and so tired that he just wants to lay down and die.
In a way, this character is the simplest character in the story. His single-minded devotion is both his greatest strength and his greatest weakness. In his character arc, it is necessary to *break* that obsessive focus on his younger brother. At the very end of the story, I wanted the impression to be that he has been stripped raw, all the rotten flesh has been torn from his bones, all the burdens (both real and imagined) have splintered and fallen away and he is left empty.
This may not seem like a happy ending, but I think it's a hopeful one. Emptiness suggests an entity that is waiting to be filled and, after this character has had his darkness stripped away, I would hope that he is filled with better things. That the reader feels that this character can and will heal himself given enough time and a new focus.
What do you consider to be a *dark character*?