When I was mother to a very young child (when she was 2 or so) I had this recurring waking nightmare of sorts: that I would be in a very tight situation- like, being burned alive or something- and I would have to rely on my baby daughter to help me to get out. It would be a simple thing: give me the key. Give me the key. GIVE ME THE KEY! Then I would ultimately burn alive because the child would surely either become distracted while trying to help me, or start crying for some random reason that I never understood. These kinds of doomsday scenarios, where my daughter failed to save me, would occur to me often, because I had nothing much to think about. My other strange fantasy was about everyone in the world dying, except for maybe five or ten percent of us. I imagined all of the streets deserted, weeds growing up. I read the World Without Us. It was good.
Then, we bought the farm. A few months after we moved out here, I realized I had not had one thought about most people in the world dying. I still had a few thoughts about my daughter failing to save me- now in farming accidents.
Those finally disappeared when she basically got a brain in her head.