I don't remember the exact line, or where it was, but there was a thread between Hermione and Hydra wherein they discuss Draco's being in love with her, and Hermione can't believe it's really true. Hydra says something like, "If his mind were a house, your picture would be in almost every room." I just loved that because it says so much about all three characters. And the nature of love itself, for that matter.