See seat map below for AA46 ORD-LHR tonight. The flight is pretty full, but I am intrigued by those "occupied" middle seats.

Nobody picks a middle on purpose, so surely they are not really occupied? Are they blocked to stay empty? Is your average passenger expected to figure that out and grab one of those window or aisle seats with the expectation of no neighbor? At what point would the middles open up? BTW I am AA Gold if status affects the seat map displayed.