This article contains spoilers for Immortal X-Men #3.
Marvel's Loki's time travel nexus. Time travel and the multiverse lie at the heart of the MCU's Phase 4 slate, but unfortunately the concepts haven't been handled in an especially consistent manner. Marvel Studios only held a summit to figure out the multiverse's rules some months after production had wrapped on a number of films and TV shows exploring the idea.
The idea of a Loki, the timeline is naturally chaotic. Any moment has the potential to create a branch in the timeline; the universe is so dynamic a person's decision to be late for work can create a separate universe. The moment where a branch s created is known as a "nexus," and the Time Variance Authority traditionally patrolled the multiverse, seeking out these nexus points and erasing branches.
Marvel Comics has just redefined the idea of a nexus, however, in Kieron Gillen and Lucas Werneck's Immortal X-Men #3. Each issue of Immortal X-Men is told from the perspective of a member of the X-Men's Quiet Council, and #3 is dedicated to the precognitive mutant called Destiny. She reveals her mind does not just explore one timeline, but all branching timelines. "A nexus is an event which pulls timelines toward it," she explains. "Meaning things after it are more predictable, for better for worse. There are other nexuses, small or large. They are waypoints on a journey -- or their terminus. Think of me as a chess player -- searching for such moments and then pushing history either away from or toward each nexus' gravity well of probability."
This is a much more elegant explanation of a nexus than the one provided in Loki, but it's with good reason. Destiny is viewing the nexus from the perspective of someone inside time, attempting to navigate it, which means her experience is naturally very different to anything described by the MCU's Avengers: Infinity War, when he used the Time Stone to view over 14 million alternate timelines to try to find one where the heroes defeated Thanos. He was able to identify the only one that offered hope, and engineer events along the right direction. Unlike Doctor Strange, however, Destiny's power means she has that experience at regular intervals.
A proper understanding of a nexus allows Destiny to navigate the timelines. Immortal X-Men #3 suggests some nexuses are minor, with only the smallest differences between the timelines; while Destiny will want to explore these, to check whether the differences increase with the age of time, in general she'll choose to leave them alone. Instead, she focuses her attention on the greater nexuses, the moments that shape history. These are the nexuses she needs to influence, in order to reach the outcome the X-Men - and, indeed, the entire mutant race - long for.
