"Slytherins being boring?"

"I left when they started wondering why you don't have any sisters."

"...yeah, come with us." And he explains how they're doing this attempted mapping.

Karen has a notation system worked out for up until they do the strings and beads thing! She's very proud of it.

Yay!

Way more interesting than speculating about his family! And not even interesting speculation, like if they were speculating about his father's secret projects or something that'd be all right. They spend most of the day wandering around and get thoroughly lost a few times.

"Next time we should bring broomsticks in case we have to go out a window."

"Oh, good idea. I asked about string we could carry behind us so we can retrace our steps, but apparently the few times people have tried that it makes things worse."

"Worse? How?"

"Peeves'll move them. Or follow them to come bother you."

"I wonder if you could get invisible string so he wouldn't do that."

"Might be worth a try. Dwimmer, can I see your notes?"

Karen hands them over.

And he puzzles over them and then hands them back and compliments their meticulousness and sighs.  "It might take all year to even figure out if it is following rules that'd make it string-and-beads mappable."

"Instead of being some way that would mean the strings would have to go through each other?"

"Yeah."

"Maybe you could make the strings go through each other."

"If the strings have to go through each other then the strings aren't doing much, any possible thing is mappable if the strings can go through each other - at least I think so - if the strings don't go through each other that'd be interesting -"

"Would it? Why?"

"I don't know if I have the words - I think if the strings don't cross than that means all Hogwarts is doing is twisting - I might be imagining it wrong -"

"Twisting and - and pinching, I guess..."

"Yeah, exactly. If you let the strings cross I don't think you can say anything about what Hogwarts is doing."

"What do you mean, you can't say anything about it -?"

"There aren't any things you can say would never happen, there aren't any routes that you could say will always work, even if sometimes they'll be five miles long..."

"There could still be bits that worked consistently, even if some of the things they did had strings crossing, though, right?"