Some writers will tell you that they are completely separate entities from their characters, having no bearing on the writer him or herself. I think that's garbage. Characters are a part of the writers who create them. Somewhere inside the writer, a part of this character that we have identified with is running amuck. No, the writer is not the character but the character is a facet of the writer. You wouldn't be able to write convincing characters if you didn't identify with the little terrors to some extent.
So I hit the 'do or die' part of my current WIP last week and since then, well, it's a good thing that I live alone. I am swearing a blue streak and not only at home but in the car, at other drivers. In the grocery store, at missing produce and products and other shoppers (under my breath). It seems that I'm grumbling at everything for the past week. I'm ready to fight. I'm not sure if this is good for my health or not - on one hand I'm venting frustrations but, on the other hand, studies show that profusely negative venting is not good for you - you just become angrier and angrier.
It's a little disconcerting that characters can influence your behavior. But I'm thinking I'm not alone in this. In between the angry music I'm listening to in order to get the mood right, I am listening to calming, peaceful music to haul me out of my self-induced insanity. And it's tiring.
I know that many people think that writers perform a core dump and vomit words onto the page, and presto, a novel appears. Writing is the most difficult thing I've done and I've done a lot of insanely difficult (and stupid, let's not forget stupid) things. The saying that writing is easy, you just open up a vein, is entirely true. You pull things out of yourself that weren't necessarily supposed to set foot out of the primordial sludge. Things that aren't nice, aren't pleasant, aren't fun and sure as hell aren't civilized and happy pink thoughts.
It's tough - especially when you set out to make your characters' lives a living hell. Which I do. I've been known to cry, to have to take walks to calm down, swear, shout and on occasion to throw things around (I limit myself to pillows so I don't damage anything). Easy? No. Necessary for writing? For me, yes.
I fully admit that I create screwed up, flawed characters. Who wants to read about a character who has ALL of his or her shit together? I don't and I'm betting you don't either. Is this a tortured part of my psyche screaming to get out? Maybe. Is this a twisted, dark side of myself erupting from my sub-conscious? Maybe. Am I a masochist? At times, I think all writers are masochists. I don't think people generally look at the darkest parts of themselves without a ton of motivation.
So when a character you're reading really gets to you? Makes you angry and squirm uncomfortably? The writer probably wasn't the happiest camper either. Who needs therapy when you can write messed up characters who explore all the dark areas? Just remember, it goes both ways - the character is influenced by the writer and the writer is influenced by the character.