I liked this story very much.
I found myself (like most other forum readers) wondering just what exactly Gus was. About halfway through the story I had decided that she was some sort of goddess of violence. Not exactly Athena (war goddess) or Artemis (huntress) but something darker, much closer to a force of nature. Electric Paladin called her a sad hurricane (I'm paraphrasing), and in my opinion that's pretty close to the truth. Probably some European goddess (they tend to have darker gods), the anthropomorphizing of violence. This would explain why she was only able to offer violence to those that offered her violence. Nothing wrong with the keg or the baby, but the idiots in the bar who offered violence, and the abusive partner who fought back got it big time.
And like a force of nature, without a suitable outlet, it rages out of control. In the absence of a lightning rod lightning will strike anywhere, in the absence of human violence Gus will destroy objects.
She kept calling it her nature, part of her, she couldn't not hit him any more than she could stop breathing. Because nothing can stop a force of nature, it can only (sometimes) be channeled. That's where the alcohol comes in. Like a river damn or a canal it serves to siphon the waters, to not exert complete control but a certain level being under control.
So to summarize, she isn't a sad, screwed up person with some kind of curse, but the physical manifestation in human form of a vast power of nature, violence.
But in retrospect, this might be because I'm in the middle of reading American Gods (and trying
very hard to make it last as long as possible).
