The tagline from this Japanese promotional trailer ("When fate must be stood up to...people shall Rock On") really explains the Screw Destiny theme of the series, and the Biometal's power to shape the Biomatch's destiny, as elaborated by Ciel.
The power of Model X in the first game is twofold: not only does it have the Double Megamerge potential that no other Mega Man can accomplish, allowing for it to bring out great powers from the other Biometal that Model A can't quite accomplish in the same way, but it's also obscenely Purposefully Overpowered as keeping it through the rest of the game (doable after completing both Vent and Aile's stories) allows you to effectively cleave your way through nearly every threat without much effort. Both of these abilities reflect the original Mega Man X's Mega Manning capacity and his infinite potential, interfacing with all Reploid weapons he absorbed and the fact that he could even non-canonically defeat a Zero in his fully-powered virus state. This also explains why it's arguably stronger solo than in the Model ZX form; Zero and X's abilities together equalize each other out and somewhat de-emphasize the buster, while Model X has no such limitations holding back its double-buster shots.
So, what's up with that red triangle that all Reploids have on their forehead? Why would you need to distinguish Reploids from humans? Well, the most logical answer is that, while humans and Reploids are closer thanever before, one might guess that they're still not 100% alike. Thus, things like medical treatment and Reploid repairing would likely put in rules like this to help identify people and get proper help during emergencies.
Also, why a red triangle, anyway? The red triangle is the symbol ofthe Resistance. Makes sense, when you consider tthe Reploid-populated Resistance were likely the most help to the humans in Area Zero while they restored society.
The red triangle could also be a reference to X, the progenitor of all Reploids, who had a red gem on his forehead.
Take a step back and look at the Biometal designs; each resembles the original character's signature weapon.
X is an X-Buster.
Z is a Z-Saber.
H has two prongs, like Harpuia's Sonic Blades.
L is the head of Leviathan's Frost Javelin.
F is Fefnir's Sodom and Gomorrah.
A is an Axl Bullet viewed from the front, with the helmet "screw" in place of the barrel.
P is one of Phantom's throwing kunai.
W fragments are shaped like Dr. Weil himself, since his mind and identity were his most powerful weapons.
As a Model W core, it's plainly a metal shard of the Ragnarok Kill Sat. This is because Ragnarok was Weil's signature weapon, both figuratively as a political tool and literally as he fused with it to fight Zero. Each Model W core also resembles a shard of a giant sword, similar to the Ragnarok core that Weil fused with.
Prometheus and Pandora's color schemes and powers embody all six of the original Biometals. Prometheus is red and purple, and uses fire (F), shadow (P), and close-ranged attacks (Z). Pandora is blue and green, and uses ice (L), lightning (H), and long-ranged attacks (X).
Why do the Pseudoroids have extra eyes? It's likely a property of Model W, and considering it is very much a Eldritch Abomination thematically, and that Humans and Reploids are and consider each other the same now the logical conclusion on exactly how this would be seen as by the people inside the setting. Add in the dialogue the Pseudoroids have and you realize that at least some of them (like Purprill) were around at least in some form before gaining the power of whatever Model they were infused with; with their absolute devotion and belief to Model W you realize that they are mutilated cultists.
Except the extra eyes motif has been around since at least the Mutos reploids. It maybe just be something high powered combat forms include.
ZX establishes that Biometals cannot defy their Biomatch's wishes, no matter how much they disagree with them. Attentive fans will recall that Dr. Wily tried to program Zero this way to suit his own purposes using what would eventually become the Maverick Virus. A big part of Zero's character is his unrelenting tenacity in fighting for the people he cares about in open defiance of his creator's programming and wishes, which played a big role in making the Four Guardians question their loyalties in the previous series and eventually side with Zero against Dr. Weil. Of course it'd be Zero's Biometal that stays behind and makes the Guardians' Biometals stop responding to their biomatches while Vent/Aile go rescue Ashe/Grey.
Veering into Fridge Horror territory, even after efforts to foster peace and equality between Reploids and humans, Reploids are still getting a raw deal. Humans get bionic bodies so they can become enhanced cyborgs, and Reploids get...an artificial expiration date, a ban on non-humanoid bodies, and a mandatory symbol on their body clearly marking them as Reploids despite the intent to make them more or less equal to humans. Even in the new Golden Age of peaceful coexistence, Reploid oppression never ends.
No, it's not meant as "oppression", but as a way to make reploids and humans "equal". The expiration date and humanoid bodies are so that they're closer to humans, and the red triangle things serve more of a practical purpose - as said above, bodily treatments of humans and reploids may still be different. Not only that, no one in the game is being discriminatory towards those who have the red triangle. So here, one goes "up" and the other goes "down", to the same new level, and it's necessary for the whole setting to work.
In fact, there's never even the suggestion of Reploid Racism, here. In the games themselves, it's never outright stated that the triangle identifies someone as a Reploid; that needs to be inferred from looking at bios and connecting the dots with certain characters. (Siarnaq's bio directly states he's a Reploid; if Prairie is, as suspected, Alouette, then the triangle you can barely see under her hat makes sense, because Alouette is a Reploid.) No one ever makes discriminatory comments; no one establishes a hatred towards humans or Reploids; and the restrictions placed on Reploids are there purely so they have the same limitations humans do, making them equal. It's not like humans are getting much better; it's kind of freaky to think about humans have lost their original bodies for pure black bionic bodies.
Albert's big minions — the rival Mega Men, Prometheus, and Pandora — are all named after the moons of Saturn. Saturn is known for its giant ring. Guess what Ouroboros, Albert's "Ultimate Biometal", is shaped like?
The four rival Mega Men are all dark reflections of the Four Guardians:
Aeolus has the refined perfectionism of Harpuia, but without any of his self-control or respect for others. He is instead consumed by uppity hubris and disdain for anything that doesn't meet his impossibly high standards.
Thetis has the arrogant playfulness of Leviathan, but without any of her self-awareness or trust in others. He is instead a selfish, nigh-sociopathical child who cannot self-examine at all.
Atlas has the passion for battle of Fefnir, but without any of his light-hearted joy or charisma. She is instead a stoic machine of war who believes that combat is the only thing that gives life meaning.
Siarnaq has the solemn dedication of Phantom, but without any of his hot-blooded loyalty. He is instead a cold, emotionless ghost of a man who doesn't trust anyone and refuses to make connections.
Why don't Grey or Ashe appear in the Model A cipher that shows how Mega Men are chosen? Because that group - Vent, Aile, Giro, Serpent, and the four rivals - were all infused with Albert's DNA at Legion. Grey and Ashe never had that procedure because they were both born with his DNA, in their own ways.
Why does Leganchor have a stereotypical "old man" personality? He's based on either a jellyfish or a cephalopod– two ancient groups of animals.
This may also explain why the time-controlling Chronoforce is a horseshoe crab.
Given how the title used for the Chosen Ones is 'Mega Man' eyebrows could be raised concerning Model Z, Model and Model A even if its just a symbolic title. X is, well, Mega Man and the Four Guardians come from his DNA so the title makes sense there. But Zero has a completely different creator and seemingly no relation to Mega Man to warrant the title making sense literally...right? Well, Zero was created by Wily to be the ultimate robot to surpass the original Mega Man, Bass and other robots that came before him. Considering his creation had the first Blue Bomber in mind, Zero would, by technicality sakes, be a Mega Man. If only one in spirit given who it was based off of. Model O/Omega would get the same treatment given they hold Zero's original body. As for Model A, regardless if you side with it being Axl or not, given that it was more than likely a Reploid's cyber-elf used to make it, and all Reploids were essentially created going off of X, then he'd also be a Mega Man.
One of the many Anti-Frustration Features introduced in Advent is that civilians, i.e. those not associated with the Guardians or the Hunters, aren't afraid of Grey or Ashe in their megamerged or A-Trans forms. This is in stark contrast in ZX, where civilians often mistook Vent's and Aile's megamerged forms for Mavericks. There's a pretty good reason for this, given that Biometals have pretty much become public knowledge following the collapse of Slither, Inc. Namely, the Hunters, who are mainly composed of civilians, have at least some basic knowledge of what a Biometal is and how valuable recovering a fragment is.
Alternatively, the heroes of Advent primarily meet other people in the Hunter Camp, full of folks from all walks of life and typically armed to fight, ready to assist those that do, or here for safety from the more dangerous reasons, meaning the fight of armored combatants is nothing abnormal here. The heroes of ZX were effectively beyond any sort of military-class Reploids or Mechaniloids around and at least partly resemble Serpent's Pantheon units that are associated with Mavericks, running around inside a false utopia of a peaceful city. Considering no one reacts to Megamerges in front of them, it implies that Grey and Ashe are simply Hunters to the rest of the Hunters regardless of physical appearance, whereas the regular citizenry freak out at non-standard combatants appearing in their vicinity.
Each of the Biometals seem to have replicated personalities of their originals — except Model W, which seems content with pure silence as it eats people's souls and cooperates with megalomaniacs. It's insinuated that Albert made them, so maybe he didn't want Weil's Ax-Crazy personality at the forefront, but as the origin of all Biometal, it brings to mind so many questions about just how warped this thing's existence is and just how much of Weil may secretly still be active within, trapped in an And I Must Scream state since his fusion with Ragnarok means all of the Model W's are made from his matter and essence.
It also makes one wonder if Model O is canon or just there for the sake of an Optional Boss unlock, and if it is something that exists, who the hell made a copy and Biometal of Omega?! Albert clearly had no interest in it or its immense power given its sealed state, and Omega was thought totally destroyed in Zero 3, so someone had to go out of their way to recreate the God of Destruction!
A long-standing debate over the black bodysuits of the Humanoids stems from the official statement that it is essentially their skin. Despite this, artwork for the audio drama "Girls Bravo" shows Aile having removed her gloves to show Prairie her calloused hands while her suit has sleeve indents, several non-Hunter civilians in the games notably lack the bodysuits, and Ashe would be effectively bottomless were it not for this suit. This implies that whether out of fashion or for better work and combat usage, Humanoids might be grafting these suits as replacements for outward flesh, which eliminates the concern of modesty but raises many concerns about just how modified all Humanoids must be internally and externally to function with it.
Giving Reploids a literal numbered lifespan under the pretenses of equality with the modern Humanoids seems a bit weird and arbitrary at first, as it's largely glossed over as background dialog. Then you find out Prometheus and Pandora have a much tighter restriction of it, and they're co-conspirators kept on a deathly leash as a result, combined with Albert and Thomas both wanting to reset the world. Chances are, the Reploid lifespan laws weren't for equality, but instead for making sure the older generations of Reploids would die off and go extinct in a subtle culling — leaving nothing but a new generation living under the Trinity's rule to go into the new world, both making sure there's no more ancient heroes to rise up again beyond the Biometals, and effectively committing a species-wide eugenics program under their noses with no one the wiser nor with any power to stop it now that it's already spread.
It's a common trait for those influenced by Model W to have red eyes. Now, note that all four of the rival Mega Men have red eyes. Is it possible that they were allowing themselves to be corrupted into Mavericks by Model W, and that in their right minds they would never go so far as to attack and kill civilians? Maybe before joining the Game of Destiny, they were reasonable individuals with hopes and dreams that wouldn't have manifested so violently.
After the "Ray of Hope" Ending in the Zero series, with Area Zero presumably being ready to start helping bring nature back to the rest of the world, we do see some of that nature in its full course here— but then Advent goes the full mile to imply that it's only around central cities, like the unnamed city of the previous game and the one here, but more importantly nearly every ounce of the nature in both games is requiring technology to aid it in ways that don't seem wholly natural. Scars of the old wars still remain from centuries prior, and the Elf Wars presumably did so much damage on top of the Eurasia damage that was being treated that most of Area Zero's natural nature simply can't sustain itself without life support systems and technological aid. Systems likely fully overseen by the Legion who, Mikhail aside, would have every reason to alter or shut them down. No wonder most of what's left of humanity would go stay in space and leave the Earth to rot — It Is Beyond Saving.
("When fate must be stood up to...people shall Rock On") really explains the Screw Destiny theme of the series, and the Biometal's power to shape the Biomatch's destiny, as elaborated by Ciel.
