After Cathy goes home, the Bella lets slip that Jill is a Royce:
isa "How is your last name a secret? Everyone knows who you are."
ji "Fuckface doesn't..."
isa "You should have told me that was a secret and why."
isa "Why is that a secret?"
ji "Never mind..."
ji "What about your secret?"
isa "What secret?"
ji "You didn't tell me Fuckface moved in here."
isa "Moved in here? He didn't move in here."
isa "I'm letting him stay here for a couple of nights and that's it."
ji "Well, you didn't tell me that."
mc "Hey...it's ok. There's no need to fight over this."
It was pretty minor but the mc called it a fight.
Also, if the mc plays guitar for the girls that night, Jill notes that he's playing Bella's favorite song and the mc remembers. Jill give's Bella a look like, "Oh, so he knows your favorite song now? He's mine, bitch!" - I might be reading in to things...
Then there's the whole weird thing in that bed scene.
Then during Yoga:
isa "How was your date?"
ji "Do you want to know about it?"
isa "I was going to ask you, but I didn't find time for it. If I had, we wouldn't have had that altercation last night..."
isa "So, I'm asking you now. How was it?"
I'd say all of that kinda fits the "cattiness" category.