Being co-prefects is a give and take. You have to pick your battles. One of the battles that I picked was to stop Ron from running plastic tubes all over the common room and placing hamsters inside of them. He was going to call it Tube City. So, yes, I do owe him one.
Ok, Harry, pay attention. I’ve brought you to the Hogwarts Library. Why? Because it’s the biggest library in the magical world. Over 20 million books. And they’re all saying the exact same thing: Listen to Hermione.
Hermione Granger [to Harry Potter, at some point, definitely]
I think Malfoy was created for the soul purpose of making me miserable.
[sarcastically] Yes. Lucius and Narcissa Malfoy decided to have a baby, not to produce their pureblood heir and have a family but to put a force on this planet to make Harry James Potter as miserable as possible.
So you get it then! Perfect!
[incredulously] Really? THAT is what you took from that?
[sighs] I'll just add this incident to the list of reasons Ron and I think you're in love with him and move on with my life.