When Carl’s kleptomania kicked in and he took the bags, Heather should have known that something was fishy. Either this man was addicted to thievery or to generosity. I firmly believe that Carl actually took pity on the poor girl. Did you see her? She barely knows how to button a shirt correctly. She’s not going to be able to take care of a whole mansion. He saw this and decided that she’d be better off with less dishes and trinkets to worry about. He was motivated by both a serious mental disorder and the need to contribute an act of kindness to the world.
But I digress. Heather should’ve known not to let a man she barely knew stay at the house by himself. She should’ve let her chef friend, Kenny, stay behind. He was enough of a cuckold that the group would’ve come back to find a new wing to the mansion built, simply to cook food for his girlfriend in.
Take also, for example, the scene at the carnival, in which Heather, an apparently functional adult, didn’t know how Ferris wheels worked. She grabbed onto a seat and rode it up and then around, back toward her attacker, the unfortunate Leatherface. Did she think that it would stop at the top and woohoo! Ride’s over. Wait. These seats aren’t filled with the skeletons of people who sat on the ride until it halted, and then died because they couldn’t get down. Some fun, right? Does she go to the bumper cars and ask about the gas mileage? Does she not eat elephant ears because she’s a vegetarian?
Heather is a dolt.
Leatherface’s activity on that date signified that he was simply trying to get Heather out of the picture and Carl was caught in the crossfire. Why would he want to let Heather be in charge of the Sawyer residence? If she was leader, it would take less than a day before Heather burned the place to the ground.
Additionally, she shouted “Do your thing, Cuz,” before Leatherface chopped the hands off the angry mayor. They were in a life and death situation, and she felt the need to take the time to make it a Batman and Robin scenario, where she called out catchphrases and he did the murdering. At that point in the film, Heather shouldn’t have even been legally allowed within 30 feet of machinery like a chainsaw. Every time Heather lights a candle, her mother wonders why the house smells like a burned tampon. If you asked Heather to name the continents, she’d tell you they were every letter except for A, E, I, O and U.
I conclude that Carl may have been struck by Leatherface, but the hulking man-child was merely an accessory in the madness that is Heather Sawyer’s stupidity. It was she that allowed Carl to go into the house that she was technically now the owner of. She was in complete control of the situation and that lack of brain power is what led to the death of a young, innocent man.
I rest my case.