Seeing Joo Heewon like this is super refreshing because it shows so much of her character and contrasts with Yesul.
Some people might call it shallow, but I think Heewon is just pragmatic - if you've proven you're useful and/or worthwhile to her, you get treated well. If you haven't, tough shit. Whereas Yesul is the kind of pure hearted person who unconsciously treats everyone the same regardless and believes that people are good enough to deserve that from her.