The moon is high. The monks outside have mistletoe garlands around their necks. It's festive! Except for the guns, and the creepy soccer-thug faces, and the ninja outfits...okay, not festive. Isobel figures out about the mistletoe and how the Wolf isn't attacking them. (If lupus deus est, then this is the shittiest fake God we've seen yet. Fear is a virus; at least Leto God Emperor of Dalek had buttresses!) She and Flora realize that the mistletoe all over the floor must've come from the Brethren. (Goes to show that they're freaked, considering that between them, Isobel and her ladies' like entire point in life is keeping the floors clean. The future is always better than the past.) Isobel orders them to gather up all the mistletoe from the floor and pile them on the table. V. album. Sticky and white. (I bring this up neither because I am gross nor because Wikipedia is crack, but because that word album always perks up my ears because of -- speaking of Willow and her colors -- alchemy. Albedo -- think Dumbledore -- is the state you reach after "washing and re-washing"; it's the white of purity. You add that to the red of tooth and claw and you get black, all the shit you and Queen Victoria don't wanna know about...but if you keep working, o ffwrnais awen, you come up with the gold at the heart of the TARDIS. Pain into gold.)
The Doctor touches the woodwork and sees the mistletoe carving on the door: "Sir Robert, did you father put that there?" Sir Robert assumes so. The Doctor murmurs to himself: "On the other door, too...A carving wouldn't be enough." He licks the woodwork. "Viscum album, the oil of the mistletoe -- it's been worked into the wood like a varnish! How clever was your dad? I love him!" Careful, careful. Love the men that have already left your world, you get hollowed out. The Doctor mumbles the sci-fi part to Rose: "Powerful stuff, mistletoe. Bursting with lectins and viscotoxins." And so, she figures, the Wolf is allergic to it. It's funny to watch this show because you have to remember, the way Rose just automatically remembers now, that everything has an alien cause. No beasties or werewolves, just aliens trying to get home. I like that about the show, but it means an extra hoop, because you're just as likely to believe in magical shit, and it's never magical: just the science of the whole world. It's one of the fun things with this show, historically: find the balance between an obvious mythical thing and the science that makes it okay. Both of which are make-believe.