Mega Man X4 - Pandora's Gift
In an earlier post, I praised Rockman X for its fantastic story, and now having played through X2, (cheating) my way through X3 (because it's bullshit), and falling in love with X4 the same way I had X1, I wanted to make a follow-up analyzing the full arc of these games before the series turned to shit in further sequels (or so I'm told)
X's story in Rockman X4 is interesting in the same simple way as the story of X1, with just enough narrative to create very interesting implications- but nothing really... happens. Same as the gameplay, X's story is very much a sort of introductory taste for Zero's story. As far as the little story in X's run goes, I do really like the gray morality presented here, in how neither the Irregular Hunters or Repliforce is in the right, both are just parties of fools pulled into a distraction of a conflict started with the false flag operation of the destruction of the Sky Lagoon. Repliforce IS justified in wanting an independent nation solely for Reploids, but their implied methods of attacking cities and stealing weapons and parts to construct their space station utopia is clearly a rush job as a means of escape from Earth. They're not attacking humans directly, Irregular Hunters ARE the aggressors here as they track down Repliforce while they try to defend themselves, but both groups are acting hastily and making poor decisions.
Zero's story, on the other hand, takes X's ending revelation, and runs with it. During X's ending, he wonders what it must be like to become Irregular, and tells Zero that if it were to happen to him, X wants Zero to be the one to take him out. Regarding your interpretation of the canonicity of things in these dual stories that cover mostly the same events but just as different playable characters, Zero isn't just exhausted and traumatized by his own experience, but knowing what he remembers now, his replies of "stop saying such stupid things, just come back to base" hit different- because Zero knows what Irregularity is. He seems to recognize that the biggest difference between an organic human and a mechanical, software-driven Reploid is the element of control, and how breaking that control causes a Reploid to be labeled Irregular.
As an English term, "Irregular" means what it sounds like, and that's true in Rockman X as well. To be Irregular is simply for a Reploid to do something unexpected. The reasoning doesn't matter, be it a virus, a choice, or Deus Ex Machina, when a Reploid breaks his programming and chooses for himself, he becomes an Irregular. This is why I much prefer the original term "Irregular" to the localized term of "Maverick". It's very clear by the time of X4 that Keiji Inafune did indeed have an overarching story planned out for the X series, and had planned things in advance when developing the first game. He specifically chose the English word "Irregular", likely due to how vague it is in its use in this series.
In Zero's ending, just before fighting the revived and newly *quite* edgy Sigma, Zero is told something that sparks a memory. Sigma found Zero during a routine Irregular Hunters mission, back when Sigma was leader of the IH. Zero was hiding out in a laboratory base, implied to be the same laboratory where Dr Wily created him in a parallel to Dr Light having created X and sealed him in his own laboratory capsule. During their savage and brutal fight, Sigma damages a seemingly integral part of the animalistic Zero's hardware, forcing him to become Irregular by breaking the directive Wily had instilled in him of killing Light, Rockman, X, or all three. Afterwards, Zero is recovered by Dr Cain and eventually rehabilitated to the point he's able to be inducted into the IH.
We have just witnessed possibly the strongest and most well-done plot twist in the X series to this point. X being discovered and replicated by Cain seemed to exclusively be a bad thing to me in my original post, but here's the kicker- Sigma is a Reploid. He's based on X. But Zero is not. Zero was developed decades ago independently by Wily, so regardless of whether X was created by Light or found by Cain, Zero would have existed, he would have been abandoned in his birthplace, and he would have been an unstoppable force of destruction. But by finding X and replicating him, by creating Sigma and the Irregular Hunters, Cain both saved the world and doomed it, since X's copy was the one to force Zero into Irregularity.
All that said, I also can't ignore the "subtle foreshadowing" during every ending since X2 (or X3, those two endings blend together to me), that X and Zero are destined to fight to the death. All of this together seems to imply that X and Zero are, in the future, bound to switch roles from their original purpose. Based on what I know about later X games, specifically with X becoming an unlockable playable character instead of the default in X7, I can definitely see this being a possibility- that is, if the shitty half of the X series follows through on its promises and acts as a satisfying ending before the time skip that leads to the Rockman Zero games.