Foster being the one next in line for the MCU's variation of the Norse God.
Foster has been portrayed slightly differently in the MCU when in comparison to the comic books, however. While Natalie Portman's version was portrayed as Hemsworth's love interest in both Thor and Thor: The Dark World, she was shown as an astrophysicist as opposed to a nurse like in Marvel comics. Following Portman's appearance in Thor: The Dark World, it was revealed the character wouldn't be returning for the third movie, Thor: Ragnarok. However, following 2019's Avengers: Endgame and Jane Foster's brief appearance in the film—albeit using deleted footage from Thor: The Dark World—director Taika Waititi confirmed Natalie Portman's return to the franchise with a significant change: her next appearance would chronicle Jane's time as the Goddess of Thunder alongside Chris Hemsworth's Thor.
This confirmation has led to much speculation and countless theories from fans of the MCU in regards to just how Jane will become Thor, given Natalie Portman's apparent exit from the franchise. With Hemsworth's Thor confirmed to be a co-lead for Love and Thunder, fans have been left to wonder just how the two versions of the iconic superhero will coexist. Jane's transition to Thor in the comics only came about when Odinson became unworthy to uphold the mantle. With fan speculation running rampant in the run-up to the film's release, and the endless possibilities brought on by the current MCU multiverse, here are all the widely known theories on how Jane Foster will take on the role of Thor in Love and Thunder.
Jane's Thor Comic-Book Origins
One of the most heavily speculated theories isn't actually much of a theory at all, given how it would be relatively easy for Marvel to simply translate Jane's Thor origins from the comics onto the big screen. In the comics—specifically Jason Aaron's Thor run—Jane becomes Thor during a stint on Asgard, acting as the representative from Midgard for the Congress of the Worlds. Before this, Jane is diagnosed with breast cancer shortly after tragically losing her husband and son in a car accident. With Thor Odinson becoming unworthy of Mjolnir following an encounter with Nick Fury, Asgard is left defenseless, save for a mysterious woman who picks up Mjolnir and fights off the likes of Malekith, The Minotaur, and the Absorbing Man. This woman is revealed to be none other than Jane, with her willingness to fight for and defend the citizens of Asgard amid her grief and cancer treatment enabling her as worthy of the powers of Thor.
While it would've been simple for Marvel Studios to directly adapt these origins a few years ago, the state of the MCU as it is now would require Love & Thunder to introduce arcs and/or characters that simply wouldn't be possible given some of the decisions the MCU has made to this point. While the creatives of the MCU have shown their ability to deftly adapt aspects of Marvel Comics, they have also shown their willingness to stray from the source material if it better serves the story or characters. With Taika Waititi directly stating that Jason Aaron's Thor comics are a direct inspiration for Love and Thunder, it's safe for fans to assume elements such as Jane's emotional and physical state will transfer onto film, however without the elements that simply wouldn't be possible given the state of the current MCU and changes it has made from comic lore regarding certain characters.
Thanos' Snap Caused Jane's Illness
One widely spread theory is more specifically aimed at how Jane's character will be written to be diagnosed with cancer, given her character's apparent good health when last seen in the MCU. Cancer is an illness that can happen for a myriad of different reasons and is often beyond human control. One theory from fans, however, is attempting to draw a connection between Jane's diagnosis and previous events of the MCU. With Natalie Portman hinting at Jane's cancer being featured in Love and Thunder, fans have pinpointed a line from Rocket Raccoon in Avengers: Endgame as a potential link. As stated by Rocket, when Thanos snapped at the end of Infinity War, Earth became ground zero for huge surges of energy due to the power of the Infinity Stones.
Fans have speculated that this surge of energy could've affected Earth and its people in some way due to the energies created by the different stones, thus causing illnesses or side effects, leading to Jane's cancer. This theory has some merit, given how projects like The Falcon and the Winter Soldier portrayed the blip as something that has affected human life outside of the, albeit temporary, death toll. However, the theory would feel slightly forced if it were to come true; with Jane's condition being shoehorned in as a side-effect of another MCU event, it would feel less consequential to Jane's personal journey, taking the spotlight away from a potential arc for Jane that could be very emotionally satisfying if done correctly.
The Reality Stone Altered Jane in Thor 2
2013's Thor: The Dark World saw Jane become the host for the Aether, or the Reality Stone. A big part of the movie revolves around trying to extract the Aether from Jane's body due to the adverse effects it is having on her. Since this is the last time Jane is seen chronologically in the MCU, this fan theory speculates that the Aether could have given Jane some long-term negative effects, which may see her diagnosed with cancer years later in the MCU timeline, thus leading to her Thor powers being brought to fruition. This theory isn't without its merits, due to the way it could feasibly work within the MCU.
With the Aether being shown to greatly affect Jane, enforced by Thor instantly rushing her to Asgard to receive magical treatment, and the revelation that Jane will die should the Aether remain in her body for too long, it is not out of the realm of possibility that the Aether could've left Foster with some long-term, life-altering side-effects. While the snap theory could be seen as unnecessary due to it being a side-effect of an event unrelated to Jane, this theory, while still being a side-effect of another MCU event, at least features something that directly affected Jane as a character, and could feed into her arc going forward, making it a well-constructed theory that certainly would work in the MCU as fans know it.
Variants and the MCU Multiverse
With Phase 4 of the MCU leaning heavily into the multiversal aspect of the MCU, many fans have surmised that the Jane Foster that becomes Thor in Thor: Love and Thunder might not be the Jane fans know from the MCU prime timeline, instead being a variant of Jane from another universe. With the Disney+ show Loki introducing multiversal elements into the MCU, and the likes of What If?, Spider-Man: No Way Home, and Doctor Strange in the Multiverse of Madness capitalizing on such plot elements, it is entirely possible that a variant of Jane with already existing Thor abilities could be the Jane featured in the Love and Thunder.
This could mean that Jane Foster being a variant wouldn't lose any of its impact by not being the Jane fans have known since 2011, considering this version of Jane would arguably be heavily featured going forward with the MCU's continued exploration of the multiverse. Also, with the way Loki specifically introduced multiversal variants, with one looking identical to Tom Hiddleston's Loki, the return of Natalie Portman doesn't discredit this theory in any way. While some fans are concerned that introducing a variant of Jane as Thor may lessen the character's arc, this theory could turn out to work best in the MCU, for nothing else other than the fact it ties heavily into promised universe-altering plot points going forward.
