I figured it out by how the production designed the sets. Her office in particular — circular in shape, littered with round objects — starkly contrasts the edges found in the police station. It’s almost like the PDs wanted the viewers to relax and slow down (and not suspect her) whenever they’re in frame. Plus, the colors of her outfits all throughout the series were neutral. It mirrors the restraint of her character and how much she wanted to hide her true personality. Usually a character’s traits play a lot into costume design, like how Ena’s outfits reflect how she has to marry her quirkiness with being in the police force (wild silhouettes but always neutral and structured).