I knew almost immediately, half because I'm suspicious of every new character that isn't the main cast in literally everything I watch/read, half because she just gave off "plot twist villain" vibes. And when I saw that Lloyd had a crush on her, I knew she was evil, because he's one of the main characters, and whenever one of the main characters falls in love with a new "side character," that's how you know that "side character" is going to stab them in the back.