Might be a controversial take but I don’t think Rumi is as oblivious as a lot of the fandom makes her out to be, and she is DEFINITELY not naive.
Think about it. Yes, she grew up likely very sheltered/isolated on Jeju Island, but also, she was a CHILD STAR. Even if she wasn’t performing, she was attending huge events like the Idol Awards with Celine when she was very young, and Celine was raising her to be a pop star. Rumi, who we know is a huge workaholic, has a ton of PR and media training and experience, more than Mira and Zoey combined. You don’t get to that position and point in your life without being able to read people (paparazzi, interviewers, journalists, etc) REALLY well. We see her gaslight and lie to Mira’s face no problem in the movie without even breaking eye contact. Yes, it’s obvious she’s hiding something, but she kept a massive secret from Mira and Zoey for years, and her lying only got bad and really noticeable when her patterns were out of control, she was stressed, and she was starting to see herself (and her heritage) differently thanks to Jinu.
And some of y’all don’t wanna hear this, but she was right about Jinu. Despite him saying that he wasn’t the guy to help her, that the Honmoon wouldn’t save him, she insisted, she persisted, she knew he desperately yearned for freedom and specifically used that to motivate him to sway him to her side, only meeting him one-on-one on her terms after their first rooftop meeting (we see her rejecting his invitations during Takedown, and she makes him go where she wants both other times they meet). Was part of her wanting to save Jinu trauma dumping and self-projection? Sure. But even when Jinu stopped trying to manipulate her (which he really only did in 1.5 interactions at most, and he wasn’t even really “manipulating” her at the fan signing, just being a smug asshole and holding what he knew over her head) and told her he wasn’t the dude to help her, she still saw and believed he could. And she was right! She was so right that Gwi-Ma literally had to step in and torture Jinu into compliance.
And finally, she single-handedly saved the world. Completely on her own, when talking to Celine, she came to the right realization and reckoning and appeared in Namsan Tower with the perfect philosophy and said just the right things to break Mira and Zoey free. And the fact that Rumi managed to convince the very dude who started the external conflict in the movie to switch sides is fucking impressive.
Bonus: I’ve seen takes that Rumi doesn’t know what sex or even a period is and like….come on, there’s NO WAY Celine skipped out on The Talk given what happened to Mi-yeong.
So yeah. Rumi is really fucking smart, and I’m tired of pretending she’s naive, oblivious, or helpless.