The following contains spoilers for Black Panther: Wakanda Forever.Black Panther: Wakanda Forever had the incredibly unenviable task of needing to address the passing of Chadwick Boseman - aka T'Challa, the Black Panther - within the MCU. As there was no intention of recasting the character, they had to create a reason for T'Challa to have an exit from the MCU in a way that would properly honor both Boseman and the character, who had become important to a lot of people. The movie did this pretty successfully and gracefully, as a large portion of the film itself was dedicated to grief and how T'Challa's family and friends dealt with his passing in-universe, mirroring how Boseman's costars were still mourning their friend.

In the movie, T'Challa succumbs to a mysterious, unnamed illness, which the opening scene shows Shuri trying to prevent by recreating the heart-shaped herb. She is not able to do so in time, and is tragically unable to save her brother from his fate. While the exact illness that befell T'Challa is never stated, there are a few fan theories circulating about what the real explanation behind the character's death might have been.

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In this fan theory found on Reddit, the original poster has a theory that the heart-shaped herb itself might have been the reason for T'Challa's untimely passing. They posit that those who take the heart-shaped herb have to continue taking it or else they will succumb to a mysterious illness, and that this is why it suddenly came upon T'Challa. This would explain why Shuri was so desperately trying to re-create the herb at the beginning of the film, as it might have been not just a catch-all cure for any illness, but the very antidote for the sickness that it caused in T'Challa's body.

Black Panther Wakanda Forever Queen Ramonda Shuri funeral memorial

This would also explain why Shuri later blames Killmonger for T'Challa's death on the ancestral plane. In Black Panther, Killmonger destroys all of the remaining heart-shaped herbs in Wakanda by burning them, and the consequences of doing so would explain why T'Challa becomes sick with something that only has one cure. Since only one Black Panther ever exists at a time, there was no reason why they would need a whole garden of herbs, so it makes sense that the large supply would be so that the Black Panther can occasionally consume another herb and fend off the illness.

Though most of the audience would just accept the terms under which T'Challa died without many questions since most current viewers understand the circumstances the movie was under in regards to Boseman's passing, it still makes sense that they would want to provide some sort of solid, in-universe reason why the character is no longer appearing. This fan theory about why T'Challa fell ill actually makes a lot of sense, and explains why Shuri struggled to save him.

However, there are still a few holes in the theory that other Reddit users in the thread pointed out. For example, why would Killmonger burn down the herbs when he also needs to consume them to avoid the sickness? It's possible that he just didn't know about it, but that seems unlikely. It's also possible he was so blinded by power that he didn't care to protect his own life - he just wanted to ensure that no one else had the same kind of power he did.

Killmonger

Others also just see the herb as a catch-all to cure all illnesses, and not that it was specifically needed to cure whatever T'Challa had. It's also possible that the implication was supposed to be that T'Challa died of cancer in the same way that Boseman did, as a way to honor the late actor. Stan Lee always had a rule in his comics that if things like cancer weren't cured in the real world, they couldn't be curable in the Marvel Comics universe either. This would explain why, even with all of the Wakandan technological advancements, Shuri was unable to save her brother.

Wakanda Forever did a great job at honoring the legacies of both Chadwick Boseman and the character of T'Challa. T'Challa still feels central to the film without being physically present, as the movie deals with the themes of legacy and grief. This is just one fan theory to explain the unnamed sickness that the character suffers from, but it was likely meant to be ambiguous for a reason. An unexpected illness with terrible consequences feels almost realistic in a way, and serves as a reminder that even the biggest heroes can still face unsolvable problems.

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