When Ron punches Draco and says "And that's the second time tonight we've saved your life, you two-faced bastard".
And also; "Snape's Patronus was a Doe," said Harry, "the same as my mother's , because he loved her nearly all of his life, from the time when they were children. You should have realised [Voldemort]". I just love that because it is so sweet, and brings a tear to my eye.
I really like this one:
"You could claim that anything’s real if the only basis for believing in it is that nobody’s ever proved that it doesn’t exist."
~Hermione Granger