Millie Merrill

The best TL;DR I can come up with rn may be this:

Ryusui coaxes Millie out of her shell. Millie offers the safe space for Ryusui to be more vulnerable.

Now for the deeper dive. Side note that I'm still working on the lore! I have most of it planned out roughly, but the specifics are still in the works and Millie's Google doc hasn't yet caught up to the notes in my head 😂 So I'll be focusing on the dynamics rather than specific events and lore for now. I'll be posting more about that soon, though!

Anyway:

Both of them had family trying to suppress and control them when they were younger. While Ryusui pursued his goals, though, Millie became very repressed and insecure.

Millie's first few months in the stone world are hard as hell for her. It isn't until the Stone Wars end and she joins the Kingdom of Science that she starts to feel a little bit more comfortable. She's still in the process of overcoming her shyness when she first meets Ryusui, though.

The thing is that Millie never got to experience much before the petrification, and her upbringing had her develop the very bad habit of bottling up her emotions. She suppressed her own wants and needs to stay out of trouble with parents, and although she's free from their influence now, she has no idea what she even wants to do.

Enter Ryusui, who's very confident and very direct with his desires. He doesn't deny himself or give up on anything he wants. Contrast that with Millie, who lacks a sense of self in a way. So when this guy shows up in her life, she's genuinely in awe. Like, "I wish I could be more like that" kind of way. She's been wondering what kind of thing to dedicate herself to, and seeing Ryusui in action is kind of a bonus inspiration 😆

So Millie keeps on trying, but again, this is still quite early on in her self-discovery journey, and she falls back into old patterns easily. Ryusui, ever The Clocker™, can not only tell she's holding back, he basically calls her out on it. Like, there's gotta be something she desires too?

They do eventually CLICK. Specifically, when they both start rambling about pastries 😂 It definitely helps Millie relax a bit more, and the more upbeat, whimsical part of her personality starts shining through. And the whole time, Ryusui keeps encouraging her to be herself, and be honest with herself. That, and he trusts in her skills a lot more than she does. (Millie is not a reliable narrator due to her own insecurities, and it's usually through everyone else that her actual capabilities become clearer.)

Treasure Island is when Millie realizes a few things.

Ryusui is even more amazing than she thought. (And she's amazed by all of her friends' skills. It comes both from genuine affection and, well, the aforementioned insecurity. Compared to everyone else, she feels terribly ordinary.)

He's caring, selfless, and reliable. (His moments with Suika being only a few examples.)

And perhaps she's starting to feel a little more than just friendship at this point.

Soon, Millie's insecurity becomes more apparent, and that turns into a whole new issue. As I already implied, she is utterly in awe of her friends, and, due to how small she makes herself, kind of puts them on a pedestal.

The problem is that this puts distance between people. Not in the sense that affection lessens, but more intimate approaches (platonic or otherwise) are difficult and less likely to happen. And that's the issue, for a while, anyway.

As I said before, she views Ryusui as a reliable, capable, and thus safe person. Feeling insecure? Shit's going down? Unsure what to do? Her eyes find him first because she knows she can rely on him like that. (Like when Senku is shot and Ryusui locks in and takes over.)

However, Millie does wonder — he takes on so much responsibility (the crew's very lives, first and foremost), isn't he ever exhausted sometimes? Carrying something well doesn't mean it isn't heavy, and all. She's never seen him falter no matter the situation, but does he ever open up to anyone? Does he ever let his guard down?

If she didn't feel so insignificant in comparison, she'd reach out. She'd ask. But ah, that pedestal.

Well, over the course of S4's events, emotions get high. Things get tough, and Millie starts noticing cracks in the facade. There is a lot more behind that steadfast captain persona that Ryusui keeps up most of the time, and she wants to see that. Just how much is he shouldering without letting anyone know? She suspects that maybe, maybe he's more open about things with Francois because of how close they are, but she can't know for sure. And she can't keep staying away in fear of screwing up when all she wants is to reach out and offer a shoulder.

As for Ryusui... lots of personal interpretation incoming, so better buckle up 😅

I already alluded to the whole captain persona thing, and I do stand by that; it's not just Millie worrying. He's responsible for so many lives; people rely on him, and he can't waver or just give up. Not that he's the type to do that, anyway. He is very open when it comes to his positive feelings and desires — negative emotions? Not so much. He really keeps up that kind of tough, but upbeat facade.

The thing is, there's so much more going on under there that we only get to see so little of. It really only starts to crack when he meets Sai again. It's been 3,700 years since he last saw his brother, whom he wanted to connect with so badly, only to be abandoned. Hell, Sai completely misinterpreted Ryusui's intent. He didn't understand what kind of person his own brother really is.

But Millie does. She wasn't fazed by Minami's complaints about him, nor did she try to suck up to him like Yo did (and probably so many others before the petrification). I wouldn't be surprised if Ryusui is used to empty flattery and all that; that's the kind of thing that comes with status and money and so on. Millie doesn't care about any of that, though. Her own awakening in the stone world sucked, and despite her social anxiety (which became obvious quickly), she went out of her way to make him, the new new guy, feel welcome. No ulterior motives, just kindness. Her awkwardness only proved her sincerity.

Speaking of Millie's sincerity... she says the darndest things to people, Ryusui included. She has a tendency to associate things with people (for example, dandelions remind her of Kohaku, and so on). The thing is, now that she's comfortable enough to actually chat openly, she will tell people things as they come to her mind. She compared Ryusui to a sunset once. Warm and vibrant. A sincere compliment that has no motive other than letting her friend know she appreciates him. Well. I am 100% convinced that genuine affection like this actually does manage to make Ryusui blush, because that is something he isn't used to. Like at all. It does things to him.

And that's the thing about Millie... She's very, very sincere, even if not with herself. She has a kind word for everyone, she cares so much and notices when someone's mood seems even slightly off. Most importantly, she makes sure to let people know she cares, in her own way. She never forgets a birthday, and she puts a ton of thought and effort into the gifts she makes by hand. She always comes up with heartfelt, deeply personal trinkets for Ryusui, because she thinks no gift might be better than one money can't buy.

That's another point. Millie really, really gets to know him. She doesn't misinterpret his greed like Minami does in the beginning, and she doesn't think of him as selfish like Sai does. She sees behind the captain persona he hides his (negative) feelings behind.

If Ryusui gets Millie to be more assertive and outgoing, then she gets him to be softer and more vulnerable. She's sincere, she's affectionate, and she's very, very gentle. She looks after him and checks on him when few others may think to do so (because again, tough captain), and while she knows not to prod too much, she always offers her support. She seeks him out to do just that after Sai rejects Ryusui so harshly, and by the time it seems that he won't be going to the moon, Ryusui seeks out Millie for comfort after. He can let down his guard around her, which is... very rare for him.

So, they have made similar experiences, if packaged differently, and they do have more in common than might be obvious at first (Millie is shy, but she's also curious and got an adventurous spirit. You better believe they both are quite excitable). But they still turned out quite differently, and that's why they complement each other.

This was long as hell, and I excluded specific lore events 😅 If you've made it this far, then thank you so much for reading! I'm in the process of finishing up the lore in Millie's doc, and I hope to start posting snippets and yaps here on Tumblr soon after. Right now, the doc is at the start of S3.