'we have to die for them to find us noble'.

Olivia Cooke as Queen Alicent Hightower

Like, I think it makes sense that as the maknae of the group, people expect Zoey to be the one using the honorific term, so she does it as part of her public persona. She usually calls Rumi, and sometimes Mira, unnie while they're doing interviews or fan meets because she knows people think it's so cute. But privately? She never does because its just not part of who she really is. Honorifics are way too formal for her so she likes to call them by silly nicknames much more, to show how close to them and safe with them she feels.

On the other hand, Mira being the "bad girl" of the group makes it so rules for her are in many ways opposite to Zoey's. While she is of course always respectful and professional, people don't really expect her using honorifics, which she is happy about after growing up on a social group where that type of respect was more expected and demanded than earned.

So while she doesn't usually adress nobody by such terms, it is a core part of how she was brought up, so her brain still corelates respect with honorifics. And while her relationship with Rumi has always had its highs and lows, it is undeniable that Rumi has earned her respect more than practically every authority figure during her childhood and teenage years.

So, sometimes the term just falls out of her mouth while they're doing something together at home, while she feels particulary soft and close to her leader or even particulary vulnerable.

It never fails to make Rumi blush, aware of everything the word really means. Which in turn makes Mira blush because no, she didn't really caught that she called her that until Right Now, thank you very much.