You watch them.
They follow their routine, bickering, unwanted compliments, etc, and you can't help but notice how perfectly in synch they are. It's quite startling, really, to see someone with supposed hatred respond so well to the object of her loathing.
Of course, to point this out to her would mean risking getting bitch-slapped.
As he steals her notes from her, you notice something. Her eyes are bright, her cheeks flushed, and her lips are slowly curving into a smile, despite the words leaving them. You realize that she's enjoying herself, berating him. If you could take a picture, you think, at this exact moment, you would be capturing their relationship in a nutshell.
But, unfortunately, you don't have a camera.
that was rather short...sorry