I have a theory that Clementine has always hyperfocussed on particular topics and people, which is why she’s managed to write in-depth books and often seems to have crushes on certain people. However, as it’s generally not socially acceptable to relentlessly only speak of one thing/person, she’s managed to mask this trait quite well.
With her new ADHD diagnosis, she is embracing neurodiversity and letting it all hang out. If she wants to hyperfocus, she’s going to knock herself out hyperfocussing.