Conception and writing . "Day One" was written by
The Last of Us series co-creator
Craig Mazin and directed by
Kate Herron. A fan of
the games on which the series is based, having played them during
COVID-19 lockdowns, Herron reached out to the
showrunners in hopes of working on an episode. Eben Bolter, her friend who worked as a
director of photography on
the first season, "put a good word in" for her. Herron was excited to speak with
Neil Druckmann, the co-showrunner who co-directed and co-wrote the games, even if she did not secure the job; she considered dressing as Ellie for her
Zoom meeting. She spoke with Mazin and Druckmann about her love for the games and series, and they later asked her to direct an episode. Herron thought they assigned her "Day One" because she talked "a lot about Ellie and Dina"; she felt their relationship was the episode's "guiding light". She enjoyed the tonal shifts, such as the discussion of
pride flags immediately before encountering the burned-out tank. She compared the tonal shifts to a
music scale, feeling some scenes built up to others—like the Capitol Hill scenes to the music store, and the television station to the subway—while others reset the tone entirely, such as Isaac's interrogation sequence. The episode's opening with FEDRA soldiers was inspired by
environmental storytelling in
The Last of Us Part II (2020), the game on which
the second season is based; the player can discover a burned-out tank and notes revealing that some FEDRA soldiers began deserting. Herron felt that focusing on Burton, a new recruit who asks questions, could help the audience learn the soldiers' dynamics. The writers were intrigued by the similarities between Ellie and the Seraphites, with both attempting to respect and protect deceased figures: Ellie with Joel, and the Seraphites with their Prophet. Druckmann felt that with the passage of time since their deaths, the deceased evolved from being real people into more of an idea. The television station scenes were inspired by the game's
stealth gameplay, which Mazin partly wanted to replicate; he showed production designer Don Macauley the in-game location as a reference before the set was built. Herron felt the nighttime setting, instead of daytime like in the game, was more frightening and intimidating. She largely planned the scene independently as the crew was working on "
Through the Valley". Mazin had intentionally added references to Ellie's love of space and astronauts in the first season (like mentioning
Sally Ride in "
Kin") to set up the second season; in "Day One", she mentions the fate of the
Apollo 1 astronauts to Dina. The Capitol Hill scenes were adapted closely from the game, in which they are optional; Druckmann was interested to discover which ones Mazin would include. They considered the music store scene especially important; it was one of Herron's favorite from the game, and she sought to make it feel "safe" rather than frightening for viewers. Ellie's performance of "Take On Me" matches the scene in the game. Druckmann sent a clip of it during filming to A-ha guitarist
Paul Waaktaar-Savoy, who was moved. Mazin thought the inclusion of the song was justified by narrative events: Dina falls in love with Ellie as she performs. Herron found the scene among the most intimidating to film, and Mazin was nervous as he felt it was one of the most meaningful to many people. He thought the scene matched the game's version in some ways while still remaining unique in others, such as the context of Ellie and Dina's relationship; by the time it took place in the game, they were already a couple. For Herron, playing a song for one's crush made the scene relatable to viewers. She filmed several different
takes, including some where Ellie avoided eye contact and Dina was "really into the song", to allow the best version to be selected during editing. Mazin approved Herron's request to add a
caterpillar in the background, which she felt reflected his willingness to collaborate. The scene in which Ellie reveals her immunity was altered to delay Dina's belief due to the series's use of tendrils instead of spores (the vector through which infection is spread in the games). Mazin considered the scene an enjoyable exercise in writing and acting, likening it to defusing a bomb. Herron found it challenging to balance the trust levels of both characters, requiring several takes. Ellie's decision to isolate herself from Dina to prove her immunity was based on Joel and Tess's similar treatment of Ellie in "
Infected". Herron wanted the scene to maintain tension until the moment Ellie and Dina kiss, making it feel earned and "like a relief, but also enough of a surprise". Their sex scene was different in the game, taking place much earlier in Jackson, and the writers' decision to move it to Seattle prompted other changes in earlier episodes. Herron appreciated the change, considering it more impactful and logical considering the series's episodic nature, but wondered if fans of the game would accept it. Mazin felt the more fearful state of
LGBTQ rights in 2003—when the outbreak occurs in the series—meant Dina was scared to reveal herself to Ellie. Herron, who
came out as bisexual in her 30s, found Dina's coming out "very relatable and beautiful" and wanted to portray it authentically, hoping viewers would realize they are not alone. She considered Ellie and Dina's relationship relatable, particularly in their mutual hesitancy.
Casting and characters was asked to tone down their guitar performance to make
Ellie appear less experienced.|alt=Bella Ramsey During the performance of "Take On Me",
Bella Ramsey (who portrays Ellie) was asked to "tone it down" and perform "worse" to make Ellie sound "more like a regular person picking up a guitar" rather than an experienced player like Ramsey. They took lessons to learn the song and felt their vocal performance—they are experienced with "more choral and operatic-like singing"—reflected Ellie's shyness during the scene. They were more nervous about the scene than their stunt work due to the character's vulnerability.
Isabela Merced (Dina) had not intended for the character to become emotional during the music store scene, but she cried due the "stunning" set and Ramsey's "angelic and pure" voice; even when Herron asked her not to cry, Merced struggled to remain composed. She felt Dina was emotional due to her love for Ellie and Joel, as well as her fear about her pregnancy and her romantic connection with Ellie. She performed the scene as if it was the moment Dina fell in love with Ellie. As a queer woman, Merced understood Dina's hesitancy to come out. She attributed the scene's authenticity to
Halley Gross for her work on both the game and series. Merced and Ramsey improvised some moments based on their mutual comfort, like adding additional kisses. Merced wanted viewers to believe that Dina "could potentially shoot Ellie in the face" and feel conflicted about it. She "went to a really dark place" to understand Dina's internal conflict and found the scene difficult to film, citing the wet weather and the gun's weight, but felt they contributed to its authenticity. Merced appreciated the scene's uniqueness as it occurred differently in the games, and found it paralleled Ellie and Riley's scenes in the first-season episode "
Left Behind". She was nervous about the "emotionally charged" scene wherein Dina reveals her pregnancy but was comforted that the cinematography mostly conceals her face; it gave her an opportunity to "hype [herself] up, and really just feel anxious". Regarding Dina's decision to continue despite her pregnancy, Merced considered her own mother, thinking "if she were able to somehow secure the safety of others and herself and her baby, nothing would really stop her".
Jeffrey Wright's casting as Isaac was announced on May 24, 2024; he reprises his role from
The Last of Us Part II, the second actor to do so after
Merle Dandridge as Marlene. Druckmann felt Wright's casting was logical as he is the correct age and appearance for Isaac. Herron wanted to support Wright's performance rather than dictate it as he was familiar with the character. The series explores more of Isaac's backstory than the game as the writers were not restricted to the perspective of the
player characters. Mazin told Druckmann about his idea for Isaac's introduction (the interrogation scene) while driving around; he wrote it like a
play. He was interested in the idea that characters like Isaac had ordinary pre-apocalypse lives, despite their chaotic present-day behaviors, prompting the inclusion of Isaac's speech about his love of cooking for his dates. Mazin wanted to communicate that Isaac had rehearsed the speech, having performed it while torturing others beforehand. Wright did not believe Isaac betrayed FEDRA, but rather that the agency betrayed him by abandoning its ethics. The WLF members Hanrahan and Burton were portrayed by
Alanna Ubach and
Ben Ahlers, respectively; their casting was announced on March 5, 2025. Herron wanted to capture that Burton is "hollowed out" in the present-day scenes. 's role in the episode was not announced before it aired.|alt=Josh Peck smiling
Josh Peck, who portrays Janowicz, had previously been mentioned in conversations about the series's casting. He watched the first season after securing the audition, which made him feel prepared after reading his scene. He read Janowicz's monologue for his audition, and considered it more interesting than typical audition lines. Peck secured the role about 2–3 weeks later, and filmed the following month. He felt the casting came "down to flavor and a look", noting the role could have been played by many other actors. Herron considered him "the best person" for the role and compared it to
Drew Barrymore's role in the opening of
Scream (1996). Peck related to Janowicz's enthusiasm to retell a favorite story to his friends, and felt removing the additional context of the post-apocalyptic world allowed him to personalize the character. He filmed for two days: the first on a street in
Vancouver, and the second on a
soundstage. Peck's casting was not announced before the episode aired, surprising many journalists, who described his appearance as a
cameo.
Filming Production for the episode began around April 2024. Catherine Goldschmidt worked as the director of photography. Kathy Kadler, an
intimacy coordinator, was present during production for the sex and interrogation scenes;
Ryan Masson, who portrayed Malcolm, was naked in the latter. The music store scene was Herron's first day of production and Druckmann's first day on set for the season, during which he showed
Pearl Jam guitarist
Mike McCready around. The set was designed and lit similar to the games; Herron and Goldschmidt referenced in-game screenshots, the latter wanting it to "feel really beautiful, really romantic". Herron focused on small elements described in the script, such as the production design detail in the store and close-up shots of instruments, wanting it to "feel like a haven" for the characters. She considered it important to capture views of Seattle as she was impressed with the area in the game. Filming occurred in Vancouver's
Downtown Eastside—replicating Seattle—with soldiers and military vehicles on May 4, and with Ramsey and Merced on horseback on May 11; production was planned late, with some businesses given four days' notice. The military vehicle's walls were removeable to allow for better camera angles. Preparatory production work began in
Nanaimo on April 22, with road closures around
Diana Krall Plaza from April 29. Around six minutes of footage was filmed from May 13–14, featuring Ramsey and Merced on horseback in Capitol Hill. Ramsey met the city's mayor,
Leonard Krog. The horse, named Jazzway, was previously featured in the television series
The 100 (2014–2020) and the film
Jurassic World Dominion (2022). The
greens department redressed Commercial Street, which Goldschmidt felt added reality to the scene. Several businesses were closed during filming and compensated by the production, and some surrounding stores saw an increase in shoppers and
online traffic, with the city's economy receiving a boost. The crew vacated Nanaimo by May 31, and the city was set to be gifted for its involvement in the series. Filming took place in
Chinatown, Vancouver, on July 8, with Ramsey, Merced, and the fictional Seraphites in a recreation of Seattle. The subway sequence was among the first
storyboarded by Herron. It was filmed in a former
paper mill found by Macauley and location manager Nicole Chartrand; its
railroad tracks were used to transport products. Macauley and his team converted the location into a metro tunnel, including with real train cars; six
Mark I model
SkyTrain cars were purchased from
TransLink in early 2024 and rebranded to represent Seattle. The stunt performers viewed the cars during pre-production to plan their movements. Herron planned the scene intensely with Goldschmidt, particularly due to the intense stunt work. Goldschmidt tested several ideas, ultimately laying the arm of a
Filmotechnic Technoscope F27
camera crane on one of the train cars to film the interior while
A-camera operator Robin Smith filmed
handheld shots. Special effects supervisor Joel Whist added hydraulic levers to rock the train cars. The scene was considered a reference to the game rather than a direct imitation. It was the result of several meetings for each element, including prosthetics and safety; Mazin considered it dangerous to film, citing the camera operator's rig suspending them in the air. The subway's red lighting was adapted from the game, established by art director John Sweeney to signify danger to the player; Mazin and Herron considered it important to incorporate and never considered omitting it. Real
flares were used for testing, with several tools used to mimic their lighting; their intensity and flicker could be controlled manually. Following Mazin's brief, Goldschmidt wanted the scene to "balance between not being able to see too much, but being able to see enough", with the thought of more infected amplifying their threat. The visual effects team increased size of the horde, though Goldschmidt felt the intensity was achieved through lighting and darkness rather than sheer numbers. Herron requested the addition of a clicker
jump scare in the scene, testing it in pre-production with the
previsualization artist, which Mazin approved. She wanted to capture the intense mood game's scene. Merced felt she bonded with Ramsey the most during the scene due to the closeness and intensity. She recalled the set "smelled like shit" as the
manure used for decorating dirt had not been sufficiently prepared in time. In the television station, the hanging bodies were played by stunt performers in harnesses. == Reception ==