I think you approach a part the same way and just find out in what's making them tick and who they are. In a movie like this you may have a little less time and few dialogue scenes and exposition scenes for your character to really get that across, and so I wanted to be able to convey that she's not somebody who's just punching a clock but she has this weird emotional investment in her job to where she does get quite myopic and that's what makes her relentless.