Warning: This article contains spoilers for The Last of Us
If you’re yet to finish up your viewing of the first season of HBO’s The Last of Us, you may want to consider turning back right here, right now – as of the next paragraph, we’re going straight into spoiler territory for the season one finale, as well as the ending of the original game.
The moral conundrum stipulated at the end of The Last of Us season one has been a hotly debated plot point ever since it aired, and for a solid decade beforehand for the game’s fandom. Did Joel deprive the world of a way out of the cordyceps-riddled apocalypse by saving Ellie from the clutches of the Fireflies? If this fan theory rings true, then absolutely not.
Based on an additional scene that the audience was treated to in the television series, u/molten_dragon over on the r/FanTheories subreddit claims that the Fireflies had it all wrong when it came to the nature of Ellie’s immunity, and killing her would not have solved a thing.
In short, the theory stipulates that Ellie’s immunity to cordyceps wasn’t a result of blood transferring from Anna’s bite via the umbilical cord moments before her birth, but from breast milk. The theory makes an assumption that Anna lied to Marlene about whether or not she fed Ellie, which isn’t all that much of a stretch considering she also lied about when she cut the cord.
The theory then goes on to unpack how the first secretion of milk following birth, colostrum, contains a significant amount of antibodies. Anna’s would have contained traces of cordyceps, as the fungus had not taken over her immune system yet. In turn, this gave Ellie’s immune system the tools it needed to fight back against cordyceps when she would get bitten in the future.
Consequently, the Fireflies’ initial hypothesis that “Ellie’s cordyceps has been with her since birth” is flawed at best, and that killing her with that theory in mind would have proved futile. While we’ve abridged the particulars of the theory for the sake of brevity, if this titillates you, we’d encourage you to go read the whole thing in the above Reddit thread – it expands the medical reasoning in a lot more detail.
While most iterations of The Last of Us have landed to universal acclaim, the recently-released PC port was just flat-out awful. There are a few good memes that sum up just how torrid the cross-platform hop turned out to be.