HBO’s The Last of Us Is Hiding Abby’s Darkest Secret in Plain Sight — Did You Catch It?

Abby, played by Kaitlyn Dever, might be immune to Cordyceps — and her father may have known all along.

Season 2 of HBO's The Last of Us landed on April 13, 2025 and left everyone with a gut-punch of an ending. And because the internet never sleeps, a pair of fan theories are blowing up — one that flips Abby's entire backstory on its head, and another that ties her to Ellie in a way that would make the Seattle drama even messier.

Quick refresher: why Abby did what she did

Kaitlyn Dever's Abby is driven by one thing: Joel killed her dad. Dr. Jerry Anderson — the Firefly surgeon Joel shot during the Season 1 finale rescue — was Abby's father. That revelation frames Season 2, and it's key to the theories fans are piecing together now.

The big swing: is Abby immune too?

Reddit has a theory that Abby might actually be immune to Cordyceps, and that her father knew it. The idea goes like this: Jerry, the same surgeon who was ready to operate on Ellie, refused to perform a similar procedure on Abby because it would have cost his daughter's life to build a cure. That would make his choice a mirror of Joel's — not cartoonishly selfish, just painfully human. Save the world or save your kid. You can see how that reframes Abby and her dad, and why Season 2's tragedy hits differently through that lens.

The wilder one: Abby and Ellie as sisters (or half-sisters)

Another theory, floating around Reddit and the franchise wiki crowd, says Abby's father could also be Ellie's father. If true, that makes Abby and Ellie sisters or half-sisters. It's not confirmed in the games, but fans point to connective tissue across The Last of Us Part II, the Left Behind DLC, and the American Dreams comics.

Here's the connective logic: Ellie's mom, Anna, was a nurse who died shortly after giving birth, leaving Ellie with Marlene and the Fireflies. Jerry Anderson was a Firefly surgeon. The two could have crossed paths through Firefly cure work before everything went sideways. Fans also cite a scene where Marlene (basically the Fireflies' top dog) challenges the surgeon with a what-if about his own daughter. Some fans paraphrase the exchange as: What if she were Abby? What if this were your daughter? The story goes that when Anna walks in, the conversation stops, and the surgeon says he's aware of the situation. If you buy that reading, Jerry might have been tangled up in both Abby's and Ellie's early lives — which would explain some eerie parallels between the two: physical grit, mirrored moral arcs, and the way their choices rhyme. Again, none of this is canon, but it is the kind of nerdy lore dive that makes this world tick.

So where is Season 3 taking this?

Season 3 is officially set to center Abby and pick up right where Season 2 cut out: Abby waking up at the WLF Stadium in Seattle. Expect the story to flip the camera to her side of the chessboard while Ellie hunts her through the city.

"This season is the Abby story."

That was Catherine O'Hara in Variety, spelling out the approach. Co-showrunner Craig Mazin also told The Hollywood Reporter that the Season 2 ending was built as a classic cliffhanger, the kind that changes the board and dares you to sit tight till they pick it up again.

• Structure-wise, Season 3 will likely track Abby's Seattle Day One, Day Two, and Day Three, but from her perspective this time.
• We should get more context on the WLF and the Seraphites — who they are beyond the headlines, why they fight, and how Abby fits into that world.
• Abby's relationships with Lev and Yara are expected to get more focus, which is long overdue if you only know her as the hammer to Ellie's nail.

The Last of Us has always been great at smudging the line between hero and villain, and Season 3 sounds like it plans to lean even harder into that. The current chatter pegs the new season for 2027, so, yeah, there is a wait.

Do you think Season 3 finally spills Abby's darkest secret — immunity, family ties, or something worse? Drop your theory. The Last of Us Seasons 1-2 are streaming on HBO Max in the US.