"What kind of owl is this? It's so cute."

"An elf owl, I think."

"If you were an animagus you could probably turn into one of these."

"So I've heard."

"You don't sound that enthusiastic."

"Do I ever?"

"And you still don't know why," says Sherlock.

"I have no idea. Or why I can get mist from the one memory but nothing from any other nice thing that ever happened to me. I'm not depressed."

"You are not," he agrees. "Have you tried to find out what it is about the book?"

"I could come up with a pattern if it were the book and something else, but it's not. It's just the one thing, not any other book I've ever gotten, or the other present I've gotten from you, or anything else that happened on my birthday, or anything else to do with Potions."

"This reminds me of a game I play with Tony," he says. "Using pieces stolen from other games, mostly. One of us creates a rule that accepts some arrangements of pieces and rejects the rest - say, 'only green pieces', or 'only a single stack of pieces' - then provides one example of an arrangement that follows the rule and one example of an arrangement that breaks it. The other has to guess what the rule is, submitting as many arrangements as necessary first to see whether they follow or break it. You've gone in thinking that the rule is 'happy thoughts', but that doesn't seem to be true. So perhaps you should start submitting other kinds of arrangements."

"Why would Patronuses work differently for me than for anybody else?"

"I have no idea, but they clearly do," he says. "Maybe I should get you another book about the Philosopher's Stone."

"Maybe," giggles Bella.

"I will, then. And I will convince Tony to do the same."

"Are there that many books about it around?" muses Bella.

"Of course. The trick is finding good ones."

"If even a bad present about the Philosopher's Stone can get mist out of my wand when learning to fly can't, then I will be very annoyed at my psychology or my magic or whatever."

"I'm sure it will be terribly sad about that."

"My psychology totally will." Pause. "Hey, can I ask you something?"

"...Yes?"

"What do you think about to get your owl?" It's still sitting on her finger, prettily sublimating.

"Tony."

"Aww."