But he's still working at the shop, so if he wants to talk to her, he can catch her when she's in to check again for potion-quality sage.

"Oh, good. I'd like two scoops."

Two scoops of sage it is.

"...So how are you doing?"

"Still undead," he shrugs. "You?"

"Still alive." She sighs. "Look, this - vaguely hostile circling thing can't be very interesting for you and I don't want you dead, what would be interesting?"

"I'm sorry, it's just uncomfortable to talk to you knowing you dislike me, and for such excellent reason."

"You weren't thinking very long-term when you accosted me, were you."

"On a number of counts, no," he says. "I also, as I believe I've mentioned, didn't know what effect I was having on you. You seemed to be reacting much as I would have, and I've never seen the threat of death as anything more than an annoying inconvenience."

"Acting like a gibbering incompetent wouldn't have accomplished anything and I had the self-possession available to spend on not doing it. Internally I was screaming. I thought you noticed everything."

"I notice plenty. I'm not a bloody telepath," he sighs. "The insides of other people's heads have always been my major blind spot."

"Thank goodness," she shivers, "that would have me externally screaming in a jiffy. I didn't think I was a particularly good actress, though."

"I could tell you were having a physiological fear reaction but I have those too and they don't mean much to me."

"It wasn't just that. I get that on roller coasters, I get it a little talking to you just now even though I trust my spell more than my gut - I also believed you were likely to hurt me and I'm whatever the opposite of suicidal is."

"Well - I'm sorry," he says.

"Before," he reminds her, "I didn't know how upset you were, or that I cared."

"How would you not know if you cared?"

"I hadn't thought about it. The entire chain of reasoning failed to occur to me."

"That sounds embarrassing."

"Yes."

She leans on a wall. She tucks her potion sage into the box from her mother's new laser pointer that she picked out of the trash to pretend it was hers. "It helps that you're sorry."

"That's good to know."

"Heh. I wonder if I could teach you to do what I do. Then you wouldn't have this problem with unpleasant surprises."

"What you do being...?"

"I think about myself. A lot. I figure out who's driving this thing." She taps her temple. "I determine what I want and what I have and how to use what I have to get what I want."

"And exactly what problem do you expect this to solve?"

"I would never, unless deprived of privacy or paper for a long time, fetch up unexpectedly finding myself caring about somebody. And if I decided I definitely didn't want to, I could probably stop, although maybe it wouldn't be wise for me to teach you that bit."

"I am fairly accomplished at introspection already and I don't think I have enough data points to accurately predict who I am going to start caring about when or why."

"I suppose that would present a problem. That doesn't mean you couldn't see it coming once it was underway."

"I did notice it when it happened."

"It looked to me almost like you came to the realization of a sudden when I started crying."

"Yes. Before that moment, I had no evidence about my reaction to seeing you cry, because I had neither seen nor imagined you crying. D'you see what I mean?"

"I think we're talking past each other," says Bella after a moment.

"Correct my aim, then."

"I have never imagined, in particular, before making up this example, imagined you crying, but because I periodically assess my thoughts on everybody worth thinking about, I wouldn't expect to find myself taken aback if you did start. Whatever happened would fit in with a pattern I already understood about myself."

"I observe my thoughts about people as they go past. But I don't see how I could observe my reaction to something I've never seen. And I don't care about people often enough to rationally predict the next target. You have hardly anything in common with the previous two."

"That's why I pick apart why I care about people - and see if the patterns apply consistently - and apply my vivid imagination to various counterfactuals. There are occasional discontinuities. I couldn't guess except by reference to other people how something like - say - doing magic might affect me, before I did it. But if I have a sample of something I can take it apart. I guessed right about how much witchcraft practice it would take to develop noticeable dependence, after I'd tried two spells. I'm not doing statistics. I'm doing - clockwork. You don't have to take apart a hundred watches, you have to know what your gears do."

"You don't share a pattern with Tony and Jarvis. I cared about them because they were my family, which you certainly aren't, and for specific things about each of them that mostly weren't common and aren't true of you as far as I can tell."

"Maybe I can't teach anyone," shrugs Bella, "maybe it's just a Bella thing."

"I'm not sure I agree with your premise. If I say the data doesn't exist, and you think it should, why must it be my skill or my architecture that's at fault and not my circumstances?"

"I think my ability would remain intact, if perhaps diminished, even in the data-impoverished situation you're describing. Given privacy and paper."

"And what arcane ritual do you undertake with those materials?"

"I write, with absolute, unflinching, honesty - albeit half in code, for all that I trust my parents to respect my privacy - so my thoughts don't escape. Occasionally there are diagrams."

"Maybe it is architectural, then. My thoughts are not known for escaping."

"I wouldn't think mine were either if I didn't go around with a metaphorical butterfly net over my head."

"Conversely, I'm not sure I could write them down if I tried. They don't come in the right format, by and large."

"I occasionally make little doodles and invent words," shrugs Bella.

Sherlock also shrugs.

"Maybe it's architectural, or idiosyncratic, or otherwise non-transferable. I don't know. It doesn't sound like you're interested, anyway."

"I am interested. Observe my interest," he says. "But I do think it's idiosyncratic in some way, because some part of the process is still lost on me."

"It works very well for me. I've never tried adapting it for anyone else; maybe I'd have to know more about you."

"More such as what?"

"Well, what format do you think in if it's not words?"

"Observed data, connections between same. Feelings. I do have some thoughts in words, they're just - unbelievably slow, compared to the rest."

"I'm not immediately coming up with a faster encoding mechanism than writing," she says. "I mean, I guess typing could be faster if you had a decent typing speed."

"I do, but not nearly fast enough."

"What I'd really like would just be directly perfect recall. But I can make paper work."

"Memory can be trained. Depending on what exactly you want to remember."

"Trained how?"

"Mine is generally obedient. But I've heard of things like mind palaces, for storing a lot of information where you can get at it whenever you need to."

"The advantage over notebooks being? Besides the obvious ones of portability and privacy."

"I don't know how it compares on storage speed, but retrieval speed has got to be orders of magnitude better."

"Hmm. Maybe I'll look it up."

"Have fun."