• She totally still levitates him when she’s annoyed with him.
• As a little kid he was very vocally indignant at this; now he just kinda sits cross-legged in mid-air and glares at her.
• Diana’s rapid aging was intentional on her part; she was trying to grow up faster so she could use her powers to find her mom. Once she’s back with her family, she starts growing up at a normal rate. This one isn’t really about them as adults, but leads into…
• When Kelly is 9 years old, Diana goes off to college in New York. He doesn’t really understand why she has to go, and he’s inconsolable for days after she leaves. But ten years later, he gets it. He did his first year at the University of Portland, but now he kind of wants to get out and see more of the world. So of course, who does he go to for advice but his big sister?
• Kelly doesn’t have powers. They’re not sure if this is because he’s half-Grimm, half-Hexenbiest and the two cancelled each other out, or because male Grimms don’t come into their powers until later. His dad was never totally clear on how that worked, and honestly…given Nick didn’t get his powers until someone he loved died, Kelly isn’t super anxious to find out.
• Diana is always a little mischievous with her magic, even once she gets past that little kid stage where everything is id.
• Diana always has a slightly difficult relationship with her father. She loves him, but they don’t always see eye to eye and she’s furious about some of the situations he put her in as a kid. Kelly is the only person she talks about this with.

That’s all for now! Thanks for asking!