Karen is informed by owl that she's a prefect. She writes her friends about that, of course.
Rebecca has had somewhat less shopping wherewithal. She just wrote him a sonata. (For Catherine she told the house-elves the precise dimensions of the doll she carried with her all the time around that age and now Catherine has one just like it, brand new and stain-resistant because house-elves.)
"Yeah. I guess maybe it doesn't take terribly long to know if you'll get on with someone."
"That charm pairs 'em - if you did more it'd get more complicated, but maybe not intractably, did you want one for Catherine?"
"That's a good idea too maybe once she's older, I was just wondering why you couldn't sell them and do remote concerts - it's not a recording charm like you were talking about but it'd still be pretty swell -"
"....ooooh. That'd be the easiest way of doing more than two, if only one had to transmit - I'll look into it -" kiss -
"And I'm married to you and I just get to keep you forever - no one talks about marriage like it's this brilliant trick to get everything you want all at once and have it for the rest of your life, I don't know why not..."
She grins at him. "They probably don't run off with fallen women from convents often enough!"
"You don't have to call yourself that, you know, you didn't do anything I didn't do ten times and no one seems to have a thing to say about me."
They do not have to do very much actual dancing! He expects she'll be pleased to hear there are demonstrative sticks in the Ravenclaw common room for everyone to borrow, now, one of the prefects asked him at the beginning of the year and got it all set up over break.
"Oh gosh. Aaron will probably tell me there should be a licensing arrangement for the notation or something."
"Probably. He has a point, being rich is really convenient and you did put a year of work into it."
"I can ask him tomorrow." Aaron didn't take anyone to the dance; he was still writing up his marriage application.
"And you and Karen invented the demonstrative stick, you can ask him if you should be turning a profit on those. The ones in the common room can be demos."