My failure means that she can pass off her failure as punishment, or another thing that I was irresponsible about and would have taken care of if I really cared. This involved buying common household items. She wanted to know why I hadn't run an errand to pick them up. Of course, as usual, no one informed me about the process around that and by the time I noticed there was a problem, no one I could ask was at home. Furthermore, I carry everything I buy on my back and have to walk or ride the bus to whatever store to purchase it. For this reason, I buy groceries every week and a half, and no more frequently than that. I also don't own a car. Carrying 10-15 pounds of groceries as I walk for a total of two hours is not something I want to repeat any more than necessary.
And, of course, I'd spent over two hours standing in the rain waiting for buses that particular day--normally, it'd be half an hour, tops. Probably more like 10 minutes. When I was waiting in the morning, the store wasn't open. In the evening, I was in the middle of conversing with someone and, frankly, didn't have the time to stop to pick anything up.
I informed her that I'd happily take over more chores at home if it meant that I could evade group shopping duties for said reasons. She changed the subject to how I needed to be more on top of cleaning so that I fit into the deadlines she established. Perfectly.
Later in the conversation she revealed that she'd just forgotten, and that in fact she wasn't punishing me.
She likes power. She's terrified of being imperfect. She doesn't want to be left alone. She's something like ... 35 years old? I don't know just how old she is, but she's been living here longer than anyone else. Something like 15 years. She's not kick-outtable.