2. The Stoner
It's a generally accepted truth that horror films have a committed moral centre - admittedly it's usually upside down and inside it, thanks to the presence of a gruesome murderer, but they generally have an agenda beyond their immediate motivation (of vengeance or unfinished business or something similar) that punishes the collected characters of the film for their various moral crimes. Drug and alcohol use - especially by teenagers - tend not to go down well with horror movie killer types, and the kill-rate tends to get higher when substances are brought into the equation, and not merely because impaired thought makes prey an awful lot easier to catch. Perhaps motivated partly by an imbalance towards amoral behaviour in the story, and also by the need to give their killer some sort of grotesque sympathetic edge, horror film-makers would have the drug-users in their films killed as punishment. Very occasionally, the stoner will be quite aware of the situation, but because he's probably the type of person who drags up conspiracy theories when he's as high as a kite and generally talks rubbish for the rest of the time. Either way, his substance abuse will see him sliced up sooner or later.