While telegraphing a killer's motive may be a horror cliche (especially when done around a camp fire), there nonetheless needs to be some kind of reasoning behind the whole killing affair. If no motive is even hinted at whatsoever, you run the risk of the audience (after seeing the short) saying... WTF was that all about and what was the point? And they most definitely will.
You NEED a reason for the guy to kill. Definitely. The essence of ALL drama ever written is conflict. To buck that is not to be a horror maverick; it's just bad writing.
Having said that, perhaps you need not flesh out the killer as much as you should flesh out the character of the woman. Lots of people by their foolish actions, bad choices, and risque lifestyles bring about their own demise. Perhaps write this woman as a sort of troubled person, whose life issues just happen - on a fateful night - run headlong into someone capable of killing given certain circumstances. The woman presents those circumstances, and the guy just goes off and WHAM. Spur of the moment - killing via act of necessity. In such a case, only the smallest detail about the killer needs to be given to justify his violence.
Last edited by Bunshinsaba (2011-06-15 23:14:13)