Easy. Demanding diva. Saw her grab one of the makeup lady's arm and say "go get me a bottle of water". No please nor thank you when she brought it to her. She was often nice to someone to their face and would roll her eyes when she'd turn around. Most of the other actors on the show hated her. In season 3 when she supposedly had her head cut off and mailed to the prison - they had a fake head on set and several of the actors were slapping it and putting it in their crotch and calling her many unflattering names. Of course she wasn't there that day.
She had explicit orders to the crew to keep the extras away from her and to not even make eye contact with her. Of course Wentworth Miller pretty much had those same orders. There were even people on set whose sole job was to keep everyone else away from them. Seriously, what had these actors ever been in before Prison Break? What exactly made them think they were so much better than everyone else?
She may have changed, that was a few years ago so I'll give her the benefit of doubt. Miller on the other hand...well you can see where his attitude has gotten him...