There's this weird thing on the train when you wake up and someone has sat down next to you while you were sleeping. You want to see who they are but you don't want to look because they aren't doing anything to attract attention to themselves. If you looked you'd be staring. Plus it'd be a very noticeable look. So you spend the rest of the trip looking anywhere other than where they are. Only when they get off you can have a look and see who your traveling companion was.