Maggie with the Carpenters?  Well duh!  I was screaming at Susan in the Changes almost the entire book.
(Funny the odd looks you get when screaming at a book.)

Harry planning the Winter Knight's demise was epic, but using Molly (How could you Harry?)
Although making Harry the Winter Knight is like giving the ring of power to Gandalf the Grey.
He could never let that happen, but he was going to save his daughter first and then take him self out.
I love this guy, can't help himself, he's a freaking superhero.

The greatest harm can result from the best intentions.  Wizard's 2nd rule