The Last of Us HBO: Why is Ellie so important?

Cameron Frew
Ellie in The Last of Us Episode 1

Why is Ellie so important in The Last of Us? In Episode 1, Joel agrees to help smuggle her out of the Boston quarantine zone – but what’s going on with her anyway?

The Last of Us Episode 1 is available to stream now. In our review, we said it achieves the impossible: adapting one of the greatest – if not the greatest – video games of all time with “respect, flair, and reaching heartbreaking greatness.”

The show follows Joel (Pedro Pascal) and Ellie (Bella Ramsey) on a cross-country trip across America amid a deadly, monstrous fungal pandemic.

In the first episode, Joel and Ellie are introduced, and we start to peel back parts of Ellie’s story – so, why is she so important?

Why is Ellie so important in The Last of Us?

Ellie is immune to the Cordyceps disease, and the Fireflies believe she’s the key to finding a cure and ending the pandemic. In Episode 1, she was bitten three weeks prior, but shows no signs of infection.

At the end of Episode 1, Joel and Tess (Anna Torv) agree to transport her to a rebel base outside the quarantine zone. Originally, Marlene (Merle Dandridge) was supposed to take her, but she was shot in a skirmish with FEDRA.

Bella Ramsey as Ellie in The Last of Us HBO show

Before they leave, Marlene tells Ellie: “You have a greater purpose than any of us could have possibly imagined.”

Just as they’ve nearly made it, they’re caught by a FEDRA soldier, who tries to test them for Cordyceps. When he gets to Ellie, she uses her knife to stab him in the leg.

However, there’s a last-minute twist: Ellie’s test is positive, yet she doesn’t appear to be infected. She was bitten three weeks ago, but she’s still her normal self. Tess is panicked by this, but knows they need to move before they’re swarmed by other FEDRA troops, so they head off on their journey.

It’s unclear how Ellie is immune. It could be the result of a random genetic mutation, or there’s another theory: her mother Anna (played by Ashley Johnson, the original voice of Ellie) was likely bitten before her death, and the antibodies were passed to Ellie before she gave birth and passed away.

The Last of Us Episode 2 will be available to watch on January 22 in the US and January 23 in the UK.

For more TLOU content, check out some of our below guides:

Joel & Tess explained | Sarah spoilers | Fungus threat is terrifying | The dog’s fate | Who is Marlene? | Why is Ellie so important? | Soundtrack choice | FEDRA & the Fireflies explained

About The Author

Cameron is Deputy TV and Movies Editor at Dexerto. He's an action movie aficionado, '80s obsessive, and Oscars enthusiast. He loves Invincible, but he's also a fan of The Boys, the MCU, The Chosen, and much more. You can contact him at