Katherine - Has to maintain professionalism but will go insane if she's professional everywhere, has to deal with Tristin, AND she's the center of boob jokes
Although, in retrospect, Elizabeth. She wasn't respected in her position, ostrisized, had an eating disorder, and when she thought all was going well, her husband died and she essentially killed herself by starvation because she was too upset to eat, and saw a hallucination of her husband whom she died in front of, who cried over her body. Also, she was mentally unstable. If you didn't get that much.
Ray-Went from a small tony stark girl with a cynical personality to a unstable druggy. She is on the fine line of going feral. Plus everyone lies to and forgets her ;-;