Cassie's been a right little snot ever since Kon died. Apart from her attitude to Ravager, there's that whole matter of having kicked Kara off the team without even consulting Robin so she could sort out her personal issues about replacing Kon.
Gawds, I miss the days when Rose was a sane teenage girl, best friends with Argent (what the hell happened to Argent?) and Cassie was a cute well-adjusted kid who grew into a natural leader rivalling Robin.