In the interest of not hitting tumblr's image limit, let's just throw out some of the information we have in one go:

It's pretty complimentary. (Yet somehow...)

The implication of the infamous "Keeping Up with Star Rail" video is that Ratio understands Aventurine better than anyone else, and Aventurine knows this. At the very least, putting all shipping aside, Ratio is the person who can explain Aventurine's behaviors best. He's the person Aventurine chooses do so. This suggests significantly more knowledge of each other's lives than the game first led us to believe.

Other people (read as: my GOAT Owlbert) perceive respect from Aventurine to Ratio, and although I read them as a bit sarcastic, the 2.1 mission logs not only repeatedly confirm that Aventurine views Ratio as smart and reliable, but that Ratio is reliable "as always," again indicating a longer and closer history of collaboration than we get to actively see in game. The devs were working hard to tell us "Penacony isn't Ratiorine's first rodeo," which is interesting--given Topaz's voiceline recommending the Trailblazer avoid working with Aventurine whenever possible, we're led to believe through 2.0 and 2.1 that not many people will willingly work with Aventurine more than once, let alone many times.

While going through psychological scrutiny from the Ghost of Christmas Yet to Come his Harmony-infused self, the "Future" Aventurine suggests that Ratio and Aventurine are quite similar, and that Aventurine puts a surprising amount of trust in Ratio, to be willing to hinge such a dangerous plan on something as untested as Ratio's ability to act. At the very least, Aventurine's own psyche is pondering on Ratio and whether or not their connection has any emotional meaning.

But despite all this evidence suggesting Ratio and Aventurine spend significantly more time with each other than we get to see in game, Aventurine's own thoughts cast strong doubt on whether he and Ratio are actually close.

Aventurine's "About Dr. Ratio" voice line suggests that Aventurine believes Ratio does not particularly like him. He seems to think that Ratio would prefer to stay away from IPC operations where possible, and it's "unfortunate" for Ratio to be stuck with Aventurine as a conversation partner. He's tolerated, rather than enjoyed. His overall impression seems to be that Ratio mostly views them as distant coworkers.

When the "Future" Aventurine suggests Ratio did not betray Aventurine willingly, actual Aventurine immediately pushes back:

(Personally I'm on the fence about whether this was real doubt or just a ploy to continue sussing out Sunday; see my other post about this scene for some more thoughts.)

But if we take this statement to be played straight, it implies that Aventurine doesn't fully believe Ratio will side with him, even (maybe especially) in dire circumstances. If this statement is real doubt, then despite considering Ratio the person who best understands him, despite building an entire life or death gamble around Ratio's loyalty... Aventurine still doesn't think Ratio even likes him.

Aventurine's not stupid or blind, so theoretically he should be able to read the situation better than that. But actually, there's plenty of evidence both in the game and outside it to suggest that Aventurine is not the most accurate judge of his own relationships to others and is a down-right terrible judge of his own worth as a person.

"Future" Aventurine suggests that one of Aventurine's deep inner flaws--the truths that he rejects about himself--is a massive inferiority complex. This is backed up well by the mission text, where Aventurine's thoughts about himself spiral into self-harm, and the scene in the maze, where "Future" Aventurine taunts our Aventurine with the unforgettable fact that his entire life was only worth pennies:

There's also pretty consistent self-deprecation, with both "Future" and real Aventurine noting several times that he's a pathetic mess of a person that other people don't trust or like.

The overall impression 2.0-2.1 left me with is that Aventurine is perfectly capable of respecting and caring for others, but virtually incapable of accepting other people genuinely respecting and caring for him.

Part of this seems to stem from the directly-stated sense that he's a failure whose only worth is in transactional exchanges, using and being used by others (there's so many layers to this--internalized racism even), but I also suspect that much of his inability to accept genuine connection from others is defensive behavior.

Aventurine's true self, Kakavasha, is deeply hidden away, like the ghost of the child that manifests from his Harmony delusion in the Dreamscape. Although Aventurine clings to that person, claiming that he has "never changed," he actively coats over his beliefs, his kindness, and his authenticity with the mask of a "cavalier gambler," with glitz and glamor and showy distractions. No one gets to see Kakavasha. No one gets to know him, because being buried deep in the dirt is the only way to remain untouchable, and fiercely keeping one's distance is the only safe bet. (For both Kakavasha and any fools who would doom themselves by daring to care for him.)

So: Canon is telling us that Ratio is one of, if not the, closest people in the world to Aventurine. But canon is also telling us that that still means absolutely nothing at all, because Aventurine won't let himself be close to anyone living.

Aventurine's senses of self-worth, trust, attachment, and safety have been warped so badly by ongoing and untreated trauma and mental health issues that, at least until the end of 2.1, I just don't think he was capable of even accepting genuine friendship from Ratio, let alone anything more.

(Interesting side note here: Ratio is actually one of the people Aventurine calls "my friend" the least. He only says it directly to Ratio a single time in all of their lines of dialogue across 2.0 and 2.1, and even then, does so only when right outside Sunday's door, while almost certainly being spied upon by the Family. Anyone who knows how often "my friend" is peppered into Aventurine's dialogue otherwise should know that the absence of the phrase is actually pretty telling. It almost feels like canon Aventurine's not even sure he can call Ratio his friend, at least to Ratio's face.)

Which makes Ratio's canon relationship to Aventurine quite sad and ironic:

From start to finish, Ratio canonically esteems Aventurine more highly than almost any other character in the game. I'm not even talking about shipping when I say that there is no character Ratio is closer to in the entire game.

At present, Ratio has only four voice lines about other characters, and of those four, Aventurine's is the only one that isn't someone from the Genius Society. The only one. Ratio's voice lines are also notably, uh, not very complimentary. Herta is "talented but not helpful to others" and "sees no one as her equal" (read as: she's self-absorbed). Screwllum is a "monarch, rather than a genius" (with the vague implications of being a tyrant), and Ruan Mei is overly ambitious and "fooling everyone."

Meanwhile, Aventurine is "our man" (who is "our" Ratio? who?) whose success "can't all be chalked up to luck," implying that part of Aventurine's success must come from skill. Ratio notes that Aventurine questions his own ability... but as far as Ratio's evaluation goes, he seems to doubt that Aventurine will ever experience a downfall. For someone who thinks 99% of the people he meets are mediocre failures scrambling around in the filth of existence, to be recognized as skilled and unlikely to fail is quite obviously glowing praise.

Then, of course, there are numerous moments that echo Aventurine's hints, implying that Ratio spends significantly more time with Aventurine than we see on-screen, that he knows Aventurine extremely well, and, although he tries (vainly) to pretend he isn't, he's clearly quite concerned with what Aventurine thinks of him.

Especially this last one. "No wonder that gambler likes you so much" is pretty intentional on the devs' part, confirming that Ratio and Aventurine are having off-screen conversations we players are not privy to, which obviously would indicate a closer relationship than the in-game cutscenes could cover.

Then, Trailblazer has the option to flat out ask Ratio to "rate" Aventurine. (Star Rail ship bait is not even subtle.)

At first, this line might read as all over the place:

"The bosses say we're partners but I wouldn't say that" -> Read as: Ratio wants people to know how their relationship is classified but doesn't want to admit to being actually invested.

"I see myself as the teacher to everyone I meet" -> Read as: Ratio at least pretends that he doesn't view anyone as his equal; everyone is either above him--geniuses--or below him--students.

"Aventurine is not that bad of a student" -> High praise; even Ratio can't pretend Aventurine's untalented.

"Actually, Aventurine's probably in metaphysical danger" -> Read as: Ratio is aware of the "void" Aventurine is experiencing and his mental struggles.

The ultimate takeaway of Ratio's "rating" actually says more about Ratio than Aventurine. When it comes down to it, Ratio's choice to answer this question for the Trailblazer instead of dismiss it tells us that Ratio has spent time quantifying and trying to define his relationship with Aventurine, is willing to at least discuss that relationship with other people (when we have no evidence he ever discusses any other personal/non-academic matters with anyone), and that Ratio pays attention to Aventurine's mental states.

Canon Ratio is not beating the allegations, I'm afraid.

But actually, I think the biggest tell about Ratio's canon relationship to Aventurine is that Ratio's behavior completely changes the moment Aventurine appears in the game.

In every single one of Ratio's other appearances, two facts are hammered home again and again:

First, Ratio hates interacting with fools and "noisy" people. He wears his plaster bust so that he doesn't even have to see them. Canonically, we're informed by both March 7th and Argenti that Ratio brought and was wearing his headpiece in Penacony. Curiously though...

The players never see it throughout 2.X--probably because 90% of Ratio's scenes are with Aventurine, and Ratio is never shown wearing his bust on screen with Aventurine--even in their very first meeting in the Final Victor lightcone. Aventurine clearly knows of the bust, but despite Ratio verbally going on and on about how Aventurine is the most "flashy" and "devoid of logic" person Ratio knows... the devs deliberately send their message: Ratio has chosen not to cut himself off from Aventurine.

Aventurine can be more "clamorous" than a screaming peacock, but Ratio will still not put up walls against him. This isn't accidental. The devs had every opportunity in the world to go the opposite route and make jokes about Ratio refusing to take the bust off in Aventurine's obnoxious presence; instead they decided that Ratio apparently has a glaring, Aventurine-shaped exception to his "I don't want to perceive you fools or be perceived by you" life rule.

This "willing to tolerate shenanigans only if Aventurine is involved" behavior continues basically throughout all of Penacony's plot. In 2.3 for example, if you turn around and talk to Ratio again on the Radiant Feldspar, he flat out says:

But there's no actual explanation for why he's there in the first place. He mentions he was assigned to watch over "the IPC's ambassadors," which theoretically should apply to Jade and Topaz, yet we never see him interacting with them in any capacity. He's never even shown in the same room as Jade or Topaz, and he's not shown doing any other form of business for the IPC on the Feldspar either. Theoretically, he could have been on the Feldspar to meet regarding the Divergent Universe... except Screwllum wasn't there yet, and Ratio doesn't mention a single word about the Divergent Universe to the Trailblazer.

The only person Ratio talks about in his dialogue on the Feldspar is Aventurine, and the only non-Trailblazer he talks to in 2.3 at all is also Aventurine, replying to him and only him in the group chat.

He looked like he might give it a shot to try to befriend Boothill and Argenti at the end of 2.3... but immediately changes his mind and leaves without saying a word to them.

It's not really a stretch to suggest that the only reasonable excuse for Ratio to attend the party on the Feldspar was if he was there for Aventurine, a behavior that he himself notes is out of character. ("A waste of time" he says, as he stands there anyway.)

But, second and even more importantly: Ratio's single most defining character trait is that he believes people need to pick themselves up. The entire point of his debut appearance in the game was to present his philosophy that if the powerful or privileged intervene to continually "save" the mediocre, ordinary people will never learn for themselves or get the chance to grow. It is in times of desperation, he says, that fools exceed their limits and reach greatness.

This is why, in 1.6, he insisted on Asta and the Trailblazer being the ones to solve the attacks happening on the space station, without relying on Screwllum or the other geniuses. Although Ratio did actively intervene a little (using the phase flame to save the researchers from death), he did so only from behind the scenes, where his actual help would not be noticed by those affected and where it had no impact on their decision-making or their struggles to solve the mystery.

He let Asta and the Trailblazer panic. He let them flounder. He even deliberately misled them at points, claiming that Duke Inferno must have kidnapped the researchers (when it was actually Ratio himself who re-routed them).

Ultimately, Ratio let Asta and the Trailblazer grow from their experiences.

This is also why he lets the Trailblazer go blazing in to fight Ruan Mei's faux emanator of the propagation, despite knowing that Trailblazer was not actually strong enough to win. Ratio watched and was ready to intervene... but in the end he did not, because it was the Trailblazer's fight to lose.

Ratio's most defining character trait is that he believes standing back and observing is the true kindness, rather than inserting oneself and denying people their autonomy or opportunities to grow.

Buttttt... then there's Aventurine, and suddenly the story is completely different.

Suddenly, Ratio isn't an observer but becomes essential to the plan. He's even walking around making big claims about being the manager of the task, flexing all of his C+ acting ability to actively carry out their mutual ploy.

In 2.3, he claims he was just there to watch, and his Penacony sticker asserts he's only "a supporting character"--yet we have never seen Ratio take a more active role in the entire game. Unlike with the Trailblazer in 1.6, he's not primarily watching events unfold from shadowy corners. He's in Penacony as Aventurine's active partner in crime.

And, even more telling--he later jeopardizes their entire mission just to ask if Aventurine needs help.

What? Huh? The character who is famous for the voice line "You look distressed. Is something troubling you? If so, you can figure it out for yourself" is suddenly offering his assistance entirely unprompted?

The guy whose motto might as well be:

Is suddenly out here throwing his own core philosophy out the window to solve Penacony's mystery for Aventurine and save him from himself in Aventurine's hour of greatest need?

A lot of people get hung up on the second half of Ratio's letter, the part about staying alive, which of course is very sweet. But I think the second half causes people to forget that the first part of Ratio's letter is, quite literally, the answer to Penacony's mystery.

Ratio gave Aventurine the answer.

This is like if your professor just gave you and you alone the score key to the final exam and then turned around to insist he "doesn't play favorites."

Of course, Aventurine is brilliant and didn't need Ratio's answer about dormancy, which makes the fact that Ratio went out of the way to give it to him even more odd. Ratio despises unnecessary repetition. If he wasn't dead worried, he would never have given Aventurine an answer that Aventurine had the power to find on his own.

And, as far as canon tells us, Ratio has never done this for anyone else.

The difference is night and day. It's literally the Gordon Ramsay meme, with everyone else in the entire game being the "fucking donkeys" to Aventurine's "Oh dear. Gorgeous."

So: Even if we entirely put aside shipping, if we look strictly at what we're given in canon:

Ratio treats Aventurine with more respect than he treats most other characters in the game.

He involves himself in Aventurine's struggles in a way that he flat out refuses to do for anyone else.

He compromises his own beliefs purely out of concern for Aventurine.

So, at least as far as we've been shown in canon, it is accurate to state that Aventurine is the closest character to Ratio--and unlike Aventurine (king of self-gaslighting), Ratio isn't even good at acting like he doesn't care.

Frankly, the whole thing is a little sad. Ratio's behavior is so blatantly out of character that a smart person like Aventurine should easily be able to determine it is genuine, but Aventurine's personal hang-ups and ongoing trauma make it difficult for him to even see that authenticity, let alone put faith in it. Even in canon, Ratio is mostly unable to help himself when it comes to Aventurine, which is especially unfortunate given how badly skewed Aventurine's perception of himself and others is by the start of Penacony's story.

PHEW! I finally made it through canon content!

Now there's just... everything else... 🫠

Well, to be honest, I don't think I could ever manage to put all my thoughts about this ship into one post. Probably not even fifty posts.

So rather than trying to say everything there is to say about Ratiorine, what I want to focus on is how fantastically these two characters just fit together. Like puzzle pieces that need to be mirror opposites in order to link, these two characters parallel each other while also perfectly filling in each other's voids. It's some of the best character pair writing I've seen in a long time (though I'm still sort of convinced it was at least 50% sheer luck on Hoyo's part), and my perspective on their ship can really be tied to my underlying perception of Ratio and Aventurine's characters as remarkably similar individuals:

It's obvious that Aventurine is not a healthy or well-adjusted adult man, but like... neither is Ratio.

Both of these characters are "not quite right" marginalized people who, at least in my interpretation, have essentially given up on even faking normality and are now just vaguely play acting their way through being functioning members of a universe that is entirely unequipped to accept them for who they are. In a world full of cyborg cowboys and people with wings growing from their heads, the game still manages to somehow convince us that Aventurine and Ratio are odd ones out.

Kakavasha can't even exist in the dystopian capitalist hellscape of the IPC's machinations. "Aventurine" isn't even a real person, just a never-ending performance, a slick, devil-may-care persona without a single ounce of substance.

Ratio, meanwhile, is a world of one, rejected from the only place he thought he could find validation and acceptance but unable to lower himself to fit in anywhere else.

Aventurine is so bad at making genuine connections that he turns everyday conversations into gambles because he doesn't believe people will care enough to keep talking to him without tangible incentive.

Ratio's insistence on treating everyone as students, not as equals, also means he has an excuse to never emotionally engage with anyone he meets. (This is not at all a textbook method of intentional avoidance to prevent any chance of social rejection. Not at all.)

At the end of the day, Aventurine and Ratio both come across as desperately lonely, and so caught up in their own situations that they really don't have the ability to climb out of that hole on their own.

Preventing them from even being able to maintain any form of relationship is also the fact that neither one of them can even find justification. Neither one of them has a reasonable answer to the question "Why am I alive?" anymore, because Aventurine's reason died on Sigonia and Ratio's reason died with an IPC invitation instead of a Genius Society letter. Though their differing perspectives have led them on opposite paths pursuing their own answers to that ultimate question of "Why should I keep living?" (Aventurine was headed toward giving up before the end of Penacony, while Ratio has invented an immeasurable, impossible goal to distract himself from feeling purposeless), both of them are pretty much miserably unfulfilled in their current lives.

They're also both violently allergic to emotional vulnerability and to having any of their flaws or true desires actually be perceived. Both of them put up insanely high walls. Aventurine pushes boundaries with everyone he meets to provoke their hatred in advance, before they can come to disdain him for his "real" flaws. He acts out harmful racist stereotypes to use others' preconceptions for advantage, manipulating every situation he's in--incidentally affirming the stereotypes against his people by doing so.

Ratio puts a physical wall of plaster between himself and others, but the plaster bust actually doesn't have anything on the mental and emotional gymnastics he's engaged in to justify his isolation from the world, doing everything in his power to convince himself that he's isolated by choice, that it's perfectly logical for Veritas Ratio to have nowhere to truly belong, no one to truly belong with. He's so mundane after all. Of course the geniuses don't want him, that's just commonsense. But everyone else is so... different, so foolish, so illogical... It just wouldn't be reasonable of him to try to become one of them either, to be their friend instead of their distant educator. (You know, if you never try to integrate with others, then they can't reject you. Ratio has learned his lesson.)

Somehow, Aventurine and Ratio are two of the most competent and successful people in Star Rail's entire universe and simultaneously also two of the most misfit, reject, dysfunctional messes in the game. Like... Blade has a better support network than Aventurine and Ratio combined. The 7000-pound murderous mech with a disabled, genetically-modified war veteran who never got to live a normal human life hiding inside it is more capable of making friends than Aventurine and Dr. Ratio.

Which is why I love that the devs decided to make their canon backstory: "Some absolute treasures in the IPC and the Intelligentsia Guild had the galaxy-brained idea of pairing Ratio and Aventurine as strategic partners." The game's writing really said: "These two characters are so socially stunted, they have to be assigned a relationship like it's homework."

They may not have it all figured out yet, but the fans see the design: Now that Ratio and Aventurine have each other, they're not alone anymore. I have never seen two characters better fit the "Is anyone going to match my freak?" meme only for the actual answer to be "Yes."

Ratio is "plays chess with himself" levels of loner weird? No problem--Aventurine is "Wanna take bets on who's going to die today?" weirder. Ratio wears a plaster bust to ward off idiots? Aventurine transforms into a monster on command, which is pretty much guaranteed to achieve the same effect.

Ratio wasn't chosen by Nous? That's fine, Aventurine's one job as a "chosen one" was to save his people and now they're all dead. Nobody can keep up with Ratio in conversation? Watch a single comment from Aventurine turn him into a fumbling mess on live television.

Ratio's inability to relate to the experiences and development of any peers his own age have left him extremely isolated and with a permanently scarred sense of self-worth? Wow, I wonder if Aventurine knows exactly what that feels like.

They just... fit.

And, changing focus a little here at the end: While I personally think that recovery from trauma requires internal motivation and self-kindness foremost, I also think that Ratio and Aventurine's relationship should be considered from the perspective of how they help to fill each other's gaps.

Unlike any connection at the Genius Society who will always evoke unpleasant memories of Nous's rejection, Aventurine isn't going to make Ratio feel intellectually inferior. Aventurine has nothing but good things to say about Ratio's intelligence, and it's even apparent that Ratio felt comfortable enough to at least mention his Genius Society woes to Aventurine, something he explicitly does not do with anyone else.

Even when it comes to social interactions, Aventurine isn't going to make Ratio feel inadequate, because honestly? Aventurine's almost as bad at them as Ratio. Aventurine is much better at faking it socially, but when it actually counts? When he's trying to be real with others? A solid 70% of the people who meet Aventurine still end up wanting to strangle him. The guy tried to apologize for threatening to detonate the Trailblazer like a bomb by buying them a model train...

Then there's this:

Aventurine is the only character explicitly called Ratio's equal in game, and more than just treating him respectfully as an equal, Aventurine also exhibits one extreme appeal that no one else in game has ever shown to Ratio: Aventurine makes Ratio feel needed. For Aventurine, Ratio is not a forgettable after-thought as he is to Herta and most of the other geniuses. He's not just "some weird guy who scolds me about school" like he is to the Trailblazer. Ratio's intellect and skill were integral to Aventurine's plan from step one to the very end. Ratio has a place in Aventurine's plots. For a character who directly assesses worth by how beneficial a person can be to others, the fact that Aventurine can make Ratio feel wanted and valued probably produced some of the strongest personal fulfillment Ratio has had in years.

On the opposite side, Ratio's in a unique position. Out of every relevant character in Aventurine's story, Ratio is the only one who has nothing to lose by choosing Kakavasha over "Aventurine." Ratio doesn't profit off Aventurine or take any expensive gifts from him, like the Trailblazer does. He doesn't need Aventurine's luck for anything at all. He'd be able to work for the IPC even if Aventurine wasn't in it. Ratio certainly doesn't want the glitz and glamour of a shallow gambling hustler persona. His work doesn't require Aventurine's continued involvement like Topaz's and Jade's does. He'd probably prefer not to know any Stonehearts at all, thank you for asking.

Outside of deliberate-acting insults about Sigonians for Sunday's sake, we're not told that Ratio has any connections to--and therefore has no preconceived biases against--Sigonians. Being a person who values self-determination and a refusal to live in mediocrity above all else, he would have nothing but esteem for how far Aventurine has managed to come despite the harsh circumstances of his life. Ratio probably wouldn't even think Aventurine's belief in Gaiathra is that strange; one of Ratio's doctorates is actually in theology.

Unlike literally everyone else in the universe who needs "Aventurine," we have every indication that Ratio's respect and admiration will only grow when he finally gets to meet "Kakavasha."

Loneliness, rejection, betrayal, a lack of understanding from others--all of these can leave wounds that only genuine, deep bonds with others can heal.

On death's doorway, in the darkest shadow, when Aventurine had to make the choice between passing on to be with the family that loved him and choosing to return to a reality without them... Ratio's letter was there, telling Aventurine the exact thing he needed to hear to choose life: Someone is waiting for you to come home.

If the resounding rejection of Star Rail's Nihility is belief in humanity's power to make meaning in our own lives through our connections to others, then the ultimate message of Ratio and Aventurine's arc in Penacony is that no one needs to be alone. The world is not as empty as you fear.

And that is a message that Ratio and Aventurine can learn best through each other.