From aloof librarian to wanting to borrow a book from senpai.
I think this artist has a good sense of how to use style and body language to (re)define a character. People often wrongly assume that how the expression is drawn is what defines their character's personality the most, but body language and physical appearance can say a lot more about who a character is, their energy levels, interests, and how they try fit in to their setting.
For example, this patch and this patch have almost the same expression, but are on two very different levels. You automatically want to draw very different conclusions about the character's setting and the kind of energy levels they have just by looking at them.
Understanding how this works is part of making great illustrations that support the dialogue and narration.