As fans of the video game knew it would, Episode 9 of “The Last of Us” ended with Joel (Pedro Pascal) rampaging through a hospital to save Ellie (Bella Ramsey) — and potentially ruining chances for a cure for humanity. On the show’s companion podcast, showrunner Craig Mazin discussed why the adaptation recreated the video game’s ending almost exactly beat for beat, saying, “[If] you change the end of ‘The Last of Us,’ you’re a fucking idiot.” That sentiment applies to its music, as well.

Composer Gustavo Santaolalla wrote the bulk of the score for both installments of the game as well as the HBO series, and did not feel any need to deviate from the sounds and themes he created for the games, because his music responds to who Ellie and Joel are as characters. “When I did the game, I wanted two sounds: one sound that is more towards the feminine side, and one that is more viral and masculine,” Santaollala told IndieWire. “The Ronroco [a Andean lute-like stringed instrument] gave me that connection with Ellie, and the six-string, the Fender vintage bass, gave me the sound of that more masculine, lower world.”

Santaollala’s work on “The Last of Us” is remarkably sparse and precise, skittering strings and minor key variations on the main themes that never live wholly in one world or the other. But the goal was to create a musical language that is more evocative than prescriptive.

“It’s not necessary that every time Ellie appears, you hear the ronroco or every time [infected appear] there’s this cue,” Santaolalla said. “In the second game, I used even more classical guitar that is an octave lower, that’s actually a continuation of the six-string bass lower world, and I also add a metal ronroco and the banjo, which stays in the middle of both worlds. I have those things like clear in my mind. But then I really work with the vision of the director and the creator of the story.”

All incarnations of “The Last of Us” are as sparing with music as the survivors of the Cordyceps infection are with Ziplock bags. The games required action tracks that could loop for as long as a player is moving through a particular level, but even so Santaollola got to take his sparse instrumental ideas and distill them down even further. On the show, he, Mazin, and games co-creator Neil Druckmann were able to be that much more intentional with cues, even bringing forward some of Santaolalla’s instrumental additions from Part II into the Season 1 score early.

The show didn’t want to change the sound of the games. But they did want to push the sound further. Core to the soundscape of “The Last of Us” are the silent spaces and deliberately “wrong” notes which make the music so achingly delicate. “I always talk about an eloquent silence, especially in music that is emotionally charged,” Santaolalla said. “When you have those silences, it kind of sucks the viewer into the screen. It’s like you go to the edge of your seat, you know?”

The viewer waits for an expected note that will complete a theme, then feels its absence when it doesn’t come. In its brief bursts, the music on “The Last of Us” gives sound to the brokenness of the old world and the twisted, precious beauty of the natural world reclaiming its place. “I find something very natural and organic in [silences]. And they also connect with the notes that the bookends of that silence,” Santaolalla said.

The sense of a grasping connection across a gap is at the very core of how the score reflects Ellie and Joel’s relationship, this tender, tragic thing that could be snuffed out at any moment. The score, therefore, sounds heartbreakingly halting, even in moments of warmth. “When we tried something different, it was OK, but this music is better,” Santaollala said. “It really connects with the story.”

So it was Santaollala’s blueprint that other collaborators on the “The Last of Us” score followed in order to deliver new action and suspense cues. Composer David Fleming, who contributed some of the most tense and action-heavy music for “The Last of Us,” particularly the cul-de-sac showdown in Episode 5, strove to be just as minimalist with a kind of music than can often be overstuffed with quick, sharp, screeching notes.

“Action scenes in video games are usually loopable things. But part of my job on a lot of these bigger action setpieces is [giving them] a narrative drive,” Fleming told IndieWire. “Craig especially is so interested in almost having the viewer feel that they’re part of the scene rather than be observing the scene, and so it was an exercise in musical restraint. The fun became where could we go sonically if we’re restricted.”

Fleming found a lot of creativity in limiting his sonic palette to sounds that might be findable in the post-Infected world; it didn’t hurt that those sounds tended to naturally pair with the sparse beauty of Santaollala’s string flourishes. “Let’s not just use any drum,” Fleming says. “The drum should have personality, whether it be a rusty barrel or like cracking wood or bowing, rusty metal. The challenge, rather than to fill it up with too many notes, was picking the right sounds, finding the right things that really make the viewer feel like they’re part of [the sequence], rather than a passive observer.”

The final sequence of Season 1 is, among many other things, a master class in using music to cue the viewers’ reactions and underscoring the emotions of a scene.

There’s the faintest hint of ronroco, tripping up the scale and then oh-so-tentatively coming down, as Ellie makes up her mind to explain what going to Salt Lake City meant to her and asks what really happened there; as Joel reaches for a platitude to make Ellie forget about saving the world and just let him protect her, the score is drowned out by the wind, emphasizing just how awkward and hollow what he says is. When Ellie says, “Swear to me,” the music returns with trembling strings as Joel lies to her. Druckmann, Mazin, and Santaolalla leave us in a silence between notes one final time as Ellie absorbs the fact he’s lied to her, saying, “OK.”

And the musical language of “The Last of Us,” as much as anything else, lets us know that Ellie and Joel’s relationship will never be the same.