You know what? I really wish I could use some of the lovely DH icons I found yesterday. But they are all spoilery to some degree, so.... *sigh*
That would, of course, be Night's Candles, my Remus-after-Sirius' death, post-"Order of the Phoenix" missing scene. I thought we might find out what happened to the mirror, so I expected that. I wasn't quite expecting to actually have a look inside Sirius' room at 12 Grimmauld Place, not in canon.
I'm more amused than sorry, though. And still rather proud of that fic.
I think this was pointed out over at Sword of Gryffindor today, and it really struck me: Harry is saved twice (well, more or less) by the love of a mother. First, when Lily sacrifices herself for him; and last, when Narcissa helps him because of her love for her own son, Draco. Gryffindor and Slytherin (I assume Narcissa Black was a Slytherin), a human shield and a really good liar, each loving her son beyond all reason--the bookends of Harry's victory.
That gives me a delightful thrill.
So, from the Slytherins, we have Regulus, Snape, Slughorn, and Narcissa coming in decisively on the side of good (for whatever motives). I thought JKR had kind of slipped up in not involving that House more in the final battle. fpb and persephone_kore pointed out to me that when reinforcements arrive, families of students and so on, Slughorn is leading them. It's entirely possible that the Slytherins only left in order to call in these reinforcements, and that their families, prudently lying low all year, might have had more resources to draw on anyway.
I like this thought quite a bit.