'The Last of Us' Season 1 Finale: Bella Ramsey on Joel's Lie and What's to Come in Season 2 (Exclusive)

The actress opened up to ET about the dramatic final moments of season 1.

Spoiler alert! Do not proceed if you haven't watch The Last of Us season 1 finale. 

The Last of Us is all about the relationship between Joel (Pedro Pascal) and Ellie (Bella Ramsey), which made Sunday's season 1 finale all the more heartbreaking.

In surprisingly fashion, however, the heartbreak this time around didn't come from the death of a beloved character -- RIP Tess, Bill, Frank, Henry, Sam, Riley and all our other faves -- but from a lie.

Having realized that the Fireflies plan for Ellie -- which involved operating on her brain to analyze her cordyceps for a possible cure -- would kill her, Joel went on a rampage, killing guards, doctors and finally Marlene (Merle Dandrige) as he broke a still-unconscious Ellie out of the hospital.

When she came to, however, Joel omitted all of his own violence from the story, telling Ellie that the hospital was attacked by raiders but that the Firefly doctors had determined she wasn't the cure and she was free to leave.

"I don't think Ellie does believe him, at her core," Ramsey told ET's Ash Crossan during an interview for The Last of Pods, an ET and Comicbook crossover podcast. "I don't think she does, but she has to force herself to believe him enough, because the thought of it not being true is too painful."

At the episode's end, a still-skeptical Ellie even asks Joel to swear that what he told her was true -- and he does.

"I think that she forces herself to to believe him and buys into her own delusion because she has to for her own sanity," the actress added. "But I think deep down she's always had a feeling."

If the truth comes to light in season 2, it's likely to cause a massive rift between the two, especially, Ramsey said, because Ellie would have "definitely" been willing to sacrifice herself for the cure.

"That's her purpose, that's the reason she's alive," she explained. "As soon as she found out that she was immune and possibly held the key to providing a vaccine to the world, that's when she felt the first time that her life mattered... I don't think she would even think twice. She would do it every time."

Joel's inability to let her is further proof of the pair's bond -- which is certain to be put to the test in the second season. As fans of the franchise know, The Last of Us Part II only steps up the gut-wrenching moments, pulling Joel and Ellie apart in its emotional storyline and giving plenty of inspiration for the episodes to come.

"Who knows what's gonna happen in season 2?" Ramsey said, promising that she was still fairly in the dark about where the show is headed. "I have sat in on some writers' meetings, but I still don't know what they're hatching up.

"It would be weird without Pedro," she said of the possibility of playing Ellie without Joel. "It would be sad, but I think that also works...My experience is so tied to him. I guess it continues to be -- and that's the point, like, it continues to be tied to him in his absence."

However, Ramsey is looking forward to some of Ellie's happier storylines in season 2, including her relationship with Dina, whom viewers caught a quick glimpse of in episode 6.

"I think that's going to be so cool, I think it's gonna be really sweet," the actress raved. "I'm glad that Ellie gets that, because of what happened with Riley. I'm glad that she is able to have a good relationship and it not end tragically for a while...she gets to experience it for longer."  

ET also spoke with series creator Craig Mazin ahead of the show's premiere, who said he would love the chance to "dive into more of the world of The Last of Us" in future seasons, exploring the lore of the games and DLC.

"We have definitely talked about seasons to come," he revealed. "I think everybody at HBO is excited about keeping it going, we want to keep it going. So as long as the audience is there and the desire's there for more, we're ready to go."

The Last of Us season 1 is available to stream on HBO Max.