Narcissa Malfoy - sometimes i think how overlooked Narcissa is. She risked everything in the series at least twice - when asking Snape to watch over Draco and in the end when she lied to Voldemort about Harry being dead. A mother's love is an amazing thing - and though she's a Malfoy, she's just as brave as many of the Order.
It didn't change so much, but there were some SURPRISING and HEARTBREAKING facts in here (what do you mean Dumbledore fell in love with Grindewald?! Huh?! And why let Arthur live and not Sirius?! Why?! WHYYYY).