alright, i'm splitting this into two sections. bear with me because I am very normal about every iteration of miguel o'hara.

let's start with his comic origins! miguel o'hara was a brilliant irish-mexican geneticist working for alchemax, a mega corporation that controls most of nueva york. he was researching how to imprint genetic codes into human physiology, which alchemax hoped to exploit for their own gain.
after being forced to do a human trial that failed (ending in someone being horribly disfigured and immediately dying), miguel tried to quit alchemax. before he could, his boss/tyler stone poisoned him with a hallucinogenic drug called rapture that bonds to your DNA. with alchemax being the sole manufacturer of the drug, miguel would become reliant on them and be forced to stay employed there or die/rely on the black market.

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now, this section is about his appearance in across the spider-verse specifically. this will have spoilers so if you haven't seen the movie, GO SEE IT RIGHT NOW!!!!!! THEN EMAIL ME YOUR THOUGHTS.

anyways.

miguel has the same origins in the movies that he does in the comics (because of course he does) so just reread that part and come back when you're done. ok? ok. now then. our first introduction to spider-man 2099 in the spider-verse series is a post-credit scene in ITSV where his holographic companion lyla is catching him up on the last few hours (regarding the events within the movie). they had been monitoring the situation and anticipated the eventual collapse of the multiverse, but it didn't! regardless, the scene shows lyla giving miguel what he calls a "goober" though she quickly corrects it to "gizmo".

i wasn't going to make this a section initially but with how much mischaracterization and blatant misinformation i've seen, i feel it's necessary to dedicate an entire section to his personality and debunk common misconceptions. this section is also lovingly curated by my dear friend D who is a fellow miguel enjoyer (in a normal way, unlike me) and has been reading spider-man since "too damn long" (their words).

is miguel a drug addict? does he need rapture? GOD NO!!!! in miguel's original run, he's poisoned with rapture by his boss/tyler stone in order to control him and make him reliant on alchemax. i explain this more in detail in the first section about his origins, but tl;dr the same experiment that turned him into spider-man also cured his rapture addiction. he doesn't need rapture, don't listen to fake news.

miguel hates miles! this is up for debate, but it's my personal belief (based on his lore as well as the events within ATSV) that miguel does not hate miles, or at the very least does not have a personal vendetta against him. i think that he's a deeply traumatized man (that is not coping well nor allowing himself to heal) and he's projecting onto miles. i think miles and miguel have a lot in common and there's a lot of parallels between the two. again, this is a hot topic and i'm happy to wax philosophical with fellow intellectuals over this but the gist of it is that miguel and miles are likely intended to be two sides of the same coin. i firmly believe that it will be expanded upon in the next movie so i'm holding off on a definite yes/no until then.

miguel killed his alternate self so that he could be happy. Are you serious. bro can't even watch people be murdered in front of him in his original run, do you really think that man can stomach killing himself just to be happy? Don't answer that it was rhetorical /j
in all seriousness, it's just not in miguel's nature and honestly this just feels like some crackpot "theory" made up by some tiktok denizen who loves angst more than miguel.