WARNING: The following contains spoilers for Rick and Morty Season 5, Episode 10, "Rickmurai Jack," which aired Sunday on Adult Swim, and Loki Season 1, Episode 6, "For All Time. Always.," streaming now on Disney+.
Rick and Morty Season 5's final episode unlocks an infinite number of alternate dimensions, abandoning the strict path imposed by an egomaniac playing God. If that sounds familiar, it is because Loki does the exact same thing for the Marvel Cinematic Universe, meaning that both shows have potentially spawned a Multiverse of Madness.
"Rickmurai Jack" reveals that every Rick Sanchez and Morty Smith, all voiced by series co-creator Justin Roiland, have been living in the Central Finite Curve, which cuts off all dimensions where Rick is the smartest being in the universe from the rest. In Loki, the Time Variance Authority (TVA) upholds the Sacred Timeline dictated by Jonathan Majors' He Who Remains, hunting anyone from any universe who strays from the path he sets out.
In He Who Remains' mind, he is acting altruistically, as he seeks to prevent a second Multiversal War caused by evil "variants" of himself. Rick from Dimension C-137 has no such excuse, having aided his other selves in creating a pocket of reality where they are dominant. They even invent a horrid array of methods for conceiving versions of their grandson Morty, just so that they all have a sidekick.
Thus, the destruction caused by Evil Morty since Rick and Morty Season 1 stems from all versions of him having lived "in one infinite crib built around an infinite fucking baby." His body count rivals that of any Rick, but he believes that what really makes him "evil" in Rick's eyes is his desire to break free from his abusive destiny. Though it requires the deaths of countless Mortys, Evil Morty does not hesitate to destroy the Central Finite Curve, exiting the episode by stepping into a dimension he hopes is not subject to Rick's omnipotence.
This stubborn pursuit of free will is mirrored by Sophia Di Martino's Sylvie, a female variant of Tom Hiddleston's Loki. Having been on the run from the TVA since childhood, she is determined to eradicate them and whoever is pulling their strings. Upon finding He Who Remains in Season 1, Episode 6, "For All Time. Always.," she finally succeeds in killing him, his warning that doing so will unleash his evil variants falling on deaf ears.
The result is that one or more variants of He Who Remains, better known as Kang the Conqueror, will appear in the upcoming Ant-Man and the Wasp: Quantumania. It is only appropriate then that the film's screenplay is by Jeff Loveness, who penned "Rickmurai Jack" and other Rick and Morty episodes. After unlocking one fictional multiverse, it will be interesting to see how he depicts the fallout from another being blown wide open.
As for Rick and Morty, removing the Central Finite Curve dethrones all the Ricks who have placed themselves above everybody else, and it is entirely possible that something worse will replace them. In finding peace, Evil Morty has potentially unleashed a whole host of new foes for everyone else to deal with, much like Sylvie. While He Who Remains was afraid of his variants, Rick's biggest threat is no longer himself but those who are the smartest beings in their universes instead of him.
In short, Rick and Morty has taken a similar approach to Loki in freeing the multiverse, even placing Evil Morty in Sylvie's vengeful role. Hopefully, just as one show has opened the door for a variety of new storylines in the MCU, the other has broadened its incredibly large canvas even further, ensuring that it remains fresh for several seasons yet.
To see Evil Morty and Sylvie's quests for emancipation, stream Season 5 of Rick and Morty on Adult Swim's website and Season 1 of Loki on Disney+.