Warning: The following article contains spoilers for Extermination #5, by Ed Brisson, Pepe Larraz, Marte Gracia and Joe Sabino, on sale now.
In a broad sense, the X-Men really aren't that complicated. They're a group of people born with fantastic powers that protect a world that hates and fears them, simple as that. But despite this simple premise, X-Men history is filled with complex plots about time travel, alternate realities, possible futures, memory wipes and radical transformations that can confuse the most dedicated X-fans.
After five years, the X-Men's latest long-running time-travel saga finally came to a close in the recently-concluded miniseries Extermination. That story saw the original five teenage X-Men -- Cyclops, Jean Grey, Angel, Iceman and Beast-- travel back into the past after spending years in the modern Marvel Universe.
However, all of the teenage X-Men changed significantly while they were living in the present day. And so, to ensure that Marvel history unfolded as it was supposed to, Jean telepathically wiped her team's memories and telepathically repressed those thoughts their adult counterparts lived through the events of Extermination.
Now, we're going to take a deeper look at the logistics of that memory wipe and the team's return to the past to see how Extermination rebuilt Marvel history without breaking Marvel's space-time continuum.
In some ways, the past five years of X-Men stories have been about ensuring that this moment unfolds as it originally did on page six of 1964's X-Men #8, by Stan Lee and Jack Kirby.
While the scene itself isn't that remarkable, it's notable for the Beast threatening to leave the X-Men after being chased by an angry mob of mutant-hating humans. At this point in time, Professor X was off exploring a cave, Iceman had just figured out how to turn himself into ice, and the team was about to have their first fight with the minor villain Unus the Untouchable in one of their earliest adventures.
Skip to 2012, and after a Phoenix-possessed Cyclops killed Professor X in the year's massive Avengers vs. X-Men crossover, the adult Beast traveled back to this specific moment in time in All-New X-Men #1, by Brian Michael Bendis and Stuart Immonen. Then, in a desperate attempt to reach out to his old friend Cyclops, he brought the teenage version of his team into their future, his present.
When the original X-Men arrived in the present day, they were astonished by what they found, and the teens decided to stay in the modern Marvel Universe to help their future counterparts and teammates. Unsurprisingly, the young X-Men struggled to deal with the knowledge of the tragedies, triumphs and monstrous transformations that their lives had in store for them.
Over the course of their adventures, each and every one of these teen X-Men went through radical personal development. While Cyclops reclaimed the childhood he never had with his space-faring father, Jean developed powerful telekinetic and telepathic abilities and matured into a strong leader. Beast began supplementing his scientific pursuits by studying magic, and Angel tried to avoid his future as Archangel by replacing his feather wings with wings made out of cosmic fire. With the support of Jean and his adult counterpart, Iceman came out of the closet in a highly-published storyline.
While some stories teased that these X-Men could've been from an alternate timeline, other stories indicated that these really were teenage versions the main Marvel Universe's X-Men. When the young Cyclops briefly died in 2013's X-Men: Battle of the Atom crossover, the adult Cyclops blinked out of existence until the teen Cyclops was healed. The group even made a few attempts to travel back to the past, but those efforts failed since they all still would've altered the timeline in one way or another.