In the comic books, the Peter Parker on Miles Morales' world died and, after the teenager was bitten by a spider inadvertently stolen by his uncle after a raid on Oscorp, he gained spectacular new powers. With that, he was faced with living up to the legacy of a superhero he'd never met, but Spider-Man: Into the Spider-Verse made some changes to the story.
That movie saw Miles bitten in similar circumstances, though it meant he was present when his reality's Spider-Man was killed by The Kingpin. Again, he was inspired to become a hero, and soon met a lot of his fellow wall-crawlers thanks to all those Multiversal shenanigans caused by the Super-Collider's activation.
In Spider-Man: Across the Spider-Verse, we learn more about how Miles became Spider-Man and why the glitching spider that bit him was labelled "42."
During a heated confrontation with Spider-Man 2099, it's revealed that Miles himself is an anomaly. The spider that bit him was pulled into his reality and should never have given him powers. They were meant for whoever was destined to be Spider-Man on Earth-42, not Earth-1610, and had Miles not been there that day, his Peter Parker would have lived and stopped what happened next.
That includes The Spot's creation; his origin is also tied to Miles in that he was there the day he destroyed the Super-Collider...the hero also hit him with a bagel. In Miguel O'Hara's eyes, this means the young web-slinger is seemingly to blame for everything that's going wrong.
Needless to say, this is a gut punch to Miles and the audience, though we're sure he'll be given the opportunity to prove he is indeed worthy of being Spider-Man in Beyond the Spider-Verse next March. As for that world without a Spider-Man, it's in total disarray and its Miles isn't Spider-Man...he's the villainous Prowler!
"A contender for the best Spider-Man film yet and easily the greatest animated movie ever made," we said in our review, "Spider-Man: Across the Spider-Verse is a jaw-dropping spectacle, a feast for the senses, and an instant Marvel classic."
Spider-Man: Across the Spider-Verse is now playing in theaters.