The following contains spoilers for The Last of Us Season 1, Episode 9, “Look for the Light,” now streaming on HBO and HBO Max.
The heartbreaking Season 1 finale of The Last of Us sets up a moral dilemma that will affect Joel and Ellie for the rest of the series. Yet, in all the examinations of whether a Cordyceps infection could really happen, not many ever focus on the end of that story. It’s almost certain that Ellie did not have to die to cultivate a cure for The Last of Us‘s infection.
In the Naughty Dog games, players eventually find notes and journals discussing the discovery of a cure. Specifically, one message says that the doctor working for the Fireflies was the “only” one who could’ve created a vaccine. One person’s belief, perhaps, but still more than the HBO series gives viewers. What’s most important is that Joel believes that what Marlene says is possible. It puts his choice to kill everyone in the proper context. To paraphrase a line from SyFy’s 12 Monkeys for The Last of Us: the only world Joel gives a damn about is the one with Ellie in it. Still, despite this clear in-character morality, objectively it’s possible that Joel didn’t prevent a cure from happening. It’s quite possible that the doctors with the Fireflies were desperate and taking a risk. Not just because they weren’t sure they could replicate Ellie’s immunity, but whether they could even get to that point. Again, this is science fiction, so there’s no right or wrong answer. The Last of Us Season 1 finale is meant to entice viewers to ask the question.
The Firefly Scientists Were Wrong: Killing Ellie Would’ve Also Killed Any Chance of a Cure
Most of the “real science applied to fake science” conversation about The Last of Us has been focused on the infection itself. Ellie’s immunity is a couple of layers deep into fictional science, but essentially the doctors were going to harvest cells and try to multiply them in a lab setting. If the doctors had gone through with their plan, they’d have killed Ellie and any chance at discerning what makes her immune and how to replicate it. Though, viewers have more information than even the scientists.
The opening scene with Ellie’s mother revealed why Ellie is immune: she cut her umbilical cord with a knife containing trace amounts of Cordyceps-infected blood. In the real world, these stem cells are used by doctors to treat any number of cancers, genetic diseases and other ailments. Unless there are some fictional scientific processes at play in this world not at play in the real one, the doctors likely didn’t even need Ellie to create the cure. They could’ve just used some blood and stem cells.
Even if there is some actual scientific basis to the plan to harvest Ellie’s Cordyceps-infused tumor, the doctors were moving too quickly. The study required to analyze Ellie’s immunity, how it worked and if it would work for other human cells would’ve taken time. How much time is uncertain, but definitely longer than it would take Joel to wake up from a knockout blow to the head. The moral ambiguity of this moment is always directed at Joel, but there is plenty to go around for all involved.
What if the Doctors on The Last of Us Finale Were Desperate Quacks?
Showrunners Craig Mazin and Neil Druckmann are the only ones who know if the vaccine would’ve worked. Hopefully, neither ever answers that particular question because the story works even better when the Fireflies are on the same morally thin ice as Joel. They didn’t know why Ellie was immune, which is what the weeks, months or years of study would’ve been for. Instead, they rushed her into surgery to cut her head open and yank out the magic cure. These aren’t the actions of medical professionals using rigorous science but rather desperate people clawing at any shred of hope they can. From this perspective, Joel didn’t “ruin” the chances of a cure; he saved them by keeping Ellie alive.
The lack of zombie action on The Last of Us came from a desire to highlight the emotional conflict of the characters over sci-fi spectacle. So, Joel’s decision to murder everyone to save Ellie is fully earned. It doesn’t matter if he’s right or wrong in an objective sense. This extends to any fallout from Joel’s actions later in the story. But, from what the show has revealed so far, Ellie probably didn’t have to die to develop a cure or, at least, study her immunity.
The Last of Us Season 1 is streaming on HBO and HBO Max, with Season 2 expected in 2024.
