There was also some flirting between Abby and Kate in the early episodes.
Abby: Admit it. You just like strappin' on a gun.
Kate: More than one.
Abby: Really? You packin' more heat than meets the eye?
Kate: Those your only tattoos?
Abby: You show me yours and I'll show you mine.
- Also in "Doppelganger" when Kate is annoyed that she's been left to handle the phones.
Kate: Hey, what is this... boys night out?
Abby: Which means Girls Night In. Transfer your phones to my lab. (Kate smiles and does so, then the two walk off hand in hand)