Warning: Spoilers for Stranger Things season 4, volume 1!

Stranger Things star David Harbour explains that the details revealed in season 4, volume 1 concerning Hopper’s tragic backstory were almost always part of the show's plan. When Matt and Ross Duffer’s nostalgia-laced series premiered on Netflix in 2016, audiences were introduced to James “Jim” Hopper, Hawkins’ (borderline) alcoholic police chief who, despite being pretty rough around the edges, is a pretty decent guy. Stranger Things season 1 flashbacks elaborate on the chief’s depression, revealing the death of his 7-year-old daughter Sara due to an unspecified illness and his subsequent divorce.

In the fight against the Upside Down’s Demogorgons and Mind Flayer, Hopper gains a new sense of purpose thanks to the relationship with Eleven, his surrogate daughter/telepathic superhero, and Joyce Byers (among others). After seemingly sacrificing himself to save his loved ones, Stranger Things season 4 picks up with Hopper in a snowy Russian prison waiting to be rescued as he and his fellow prisoners prepare to combat a Demogorgon. “Chapter Five: The Nina Project” finds Hopper at his lowest point, where he reveals to Dimitri (and the audience) how, in Vietnam, his unit unknowingly mixed the chemicals for Agent Orange. Those in his unit went on to have kids who developed congenital disabilities and other illnesses. In Sara’s case, she was diagnosed with cancer.

Related: Stranger Things Really Didn't Need To Explain Sara Hopper's Death

In a recent interview with The Wrap (via Yahoo), Harbour discusses how Hopper’s season 4 monologue makes him indirectly responsible for his daughter’s death. According to the actor, further explaining Hopper’s immense guilt was always part of the plan. Read the full quote below:

It’s something that the Duffers and I had discussed from day one of the pilot—what’s up with Sarah’s cancer? Because I’ve always been interested in this “Memento” idea of a man chasing himself, as being the ultimate nemesis of himself. I just love that idea. I was like, “Why does he feel so guilty about Sarah’s death? It’s cancer, nothing in his control.” I was like, “Well, let’s make it a tangible thing. Let’s make it physically toxic and poisonous and actually responsible for her death.”

We have this backstory throughout, but I wasn’t sure that we’d ever get a chance to play it. It was just one of these things that we knew I could pay little homages to in various ways with emotion, but it wasn’t something I ever thought I would actually say. Then we had this opportunity, and it was really exciting to read it after they wrote it. It was beautiful, and the great thing about this season is Hopper barely speaks in the first four episodes. It’s basically him breaking his ankles, trying to get out of chains, and then eating peanut butter and curled up in bed or doing pushups in a cell. He doesn’t say anything.

Then he gets back, and he’s at his lowest point, and he just unleashes. It’s almost like a flood of this mess that he’s been keeping inside. I like the randomness of it. There was something about this that didn’t make sense that he was saying it right then, and there was something quite emancipating about, you’ve done this thing, you got out and then you’re right back to where you started. It was like you’re carrying around this weight, and you just have to rip that out and just let it fall where it falls. It was about the fact that he finally was at his lowest point and had to release his dark secret. Almost like a weight, he had to just shed it.

stranger things hopper sara death

While stuck in the Russian prison, Hopper has been beating himself up by questioning his life choices. After being tortured and barely talking for episodes, it makes sense that he would talk about the trauma he’s been struggling with since Stranger Things season 1. As if cancer wasn’t bad enough, it was certainly surprising that Stranger Things decided to directly link Sara’s illness to Hopper’s past. While it doesn’t necessarily change how the audience views him, it intensifies Hopper’s guilt and amplifies his desire to do right by Eleven—who still thinks he died beneath the Starcourt Mall. Now, he’s determined to help his loved ones more than ever.

At the end of Stranger Things season 4, volume 1, Joyce and Murray succeed in saving Hopper and Dimitri from the Demogorgon, but are still stuck inside the Russian prison. Not only will the four have to escape the prison—which appears to be stocked with supernatural happenings—but they must also find a way back to their family, with Steve and Nancy currently dealing with Vecna. It remains to be seen if Hopper can redeem himself in his own eyes when Stranger Things season 4, part 2 drops on July 1.

More: Stephen King Missed The 1 Good Thing About Stranger Things Season 4 Split

Source: The Wrap (via Yahoo)