Disclaimer: I don't own The Powerpuff Girls or anything related to it
Professor Utonium was very observant. He didn't observe the trees and flowers, well occasionally he does when he's not working in the lab, or even how people acted. He observed his now 15-year-old girls, everything to do with them, from favorite things to their growing abilities. He kept a file in his lab on the things he found out. He noticed even the smallest things, like the small difference in their hair. But he also knew more private things about them. Like crushes. He looked out the window and looked at his girls fighting the Rowdyruff boys. He took in their hesitation to punching or kicking them. He also saw the feeling in their eyes. He glanced at the Rowdyruff boys. He noticed the same things about them, but it was deeper. He smiled to himself. They had to admit it. But they wouldn't right now. They were trying to fight it. And he respected that.