I once took an overnight flight from the west coast to the east coast. The flight wasn't very crowded and I intentionally picked a seat away from other ocupied seats.

I get on the plane, as I'm warking back to my seat I notice there's entire rows that are empty. So instead of picking a seat in an open row, and this. fucking. guy. picked the window seat closest to my aisle seat, and he talked for most of the flight. In hindsight I should have just sat somewhere else when I first noticed him.