I would say it's partially the tone, but she IS out of character (where did her accent go??!). Harley DOES have a dark side in her obsession for the Joker and she DOES have a mean streak, it's just hidden by her bubbly personality. I think a writer can go dark in her how she shows her love for him, but that's not what Lieberman was doing. Yeah, that exchange was good. I also liked "Confucius say come to roof now!" I don't deny there were funny exchanges but it's the overall that tanked.