Ideas for you!

Benny Green - Davy Galloway's been poking around thinking about getting at the sunken treasure, and I suspect that means he's creeping into Pirate territory, idk how Benny feels about that.

Christine Pennyfeather - Arabella Somerville will probably spend too much time and money in the bookstore, and would be totally aghast that Christine doesn't want to keep them. Who doesn't love books? Arabella'd definitely try to convince Christine that books are great.

Edward Seymour - Similar vein, I imagine would (probably literally) try to chase down Edward to try and teach him something. Or just, do slightly dangerous science with him to try and get him interested in school.

Pony McBride - I think Arabella would take particular insult that he was selling snake-oil, but she is a very gullible person and could easily believe he was well intentioned but bad at his job