Wall outlet only works when AFI breaker is OFF?
Mystery solved. We had a bit of a Car Allergic to Vanilla Ice Cream problem. Turns out the bedroom outlet is on the same switch as the basement lights. Whenever I went down to the basement and flipped a breaker, I left the basement lights on when I came back upstairs, since I was planning on going back down to flip the breaker back. So, because the basement lights were on, the outlet in the room was powered when I got back upstairs. Not the most intelligent wiring decision in the world, but not rampantly dangerous either.