Spoiler alert! The following contains details from the "Stranger Things 4" finale.
Sadie Sink, 20, who plays Max, says she learned several months before filming that Max’s heart would temporarily stop, she would lose her sight and end up in coma.
“They did call me and give me a warning before I read the last episode, because Max's fate is certainly up in the air. So they kind of gave me a warning, and then I read it and it's a very shocking ending,” Sink tells USA TODAY, referring to the show's executive producers, Matt and Ross Duffer.
Caleb McLaughlin, 20, says he didn’t know the Duffers would shoot the scene where his character, Lucas, shrieks at Max's (presumed) death until that day.
“I didn't know we were doing that scene, and I was like: ‘Oh, OK, cool. Just give me 10 minutes to get these tears up,’” McLaughlin says.
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Emotions ran high on set while filming, Sink says, but she felt lucky to have McLaughlin by her side.
“We're very, very close friends and we trust each other so much, so having him as a scene partner for that moment felt very safe and comfortable,” Sink says. “And to do that kind of thing, where the stakes are so high and emotions are so high and you're in such a vulnerable place, I think it was nice to have each other's support while filming.”
When Sink learned Max would be even more of a central focus this season, she made sure to do her character justice.
“In an ensemble show where there's so many plot lines happening and you can only give so much attention to each character, for them to trust me with this, I was really grateful,” Sink says.
Sink’s performance in the season's fourth episode became an iconic moment for the series, as it shows Max nearly being killed by Vecna in the Upside Down before her friends play her favorite song, Kate Bush’s 1985 hit “Running Up That Hill (A Deal With God).” The song empowers Max to fend off Vecna and escape death.
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The episode boosted the 1985 hit to the No. 1 spot on iTunes.
Sink says she wants to tell Bush how much her music meant to her (and her character), but she had never heard of the singer before reading the script. (Afterward, she listened to the song repeatedly until it became “engraved in a special place in my mind.”)
“I would love to meet her in person one day, but I'm also not convinced that she's a real person. So I would love to meet her and to prove that she is real, and also thank her.”
McLaughlin says he was surprised the season sparked a cultural revival for the song, but he's happy Bush is receiving even more recognition with a new generation.
The Duffers said on the Happy Sad Confused podcast that viewers will see many of the pairings from the first season reunite in the fifth and final season.
McLaughlin says he hopes to have more scenes with Millie Bobbie Brown (Eleven) and Finn Wolfhard (Mike Wheeler), adding he has come a long way as an actor since starting the show as a teenager.
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McLaughlin says the series' ending is already on the cast's mind. Sink recently sent a Twitter video of them, Wolfhard, Noah Schnapp (Will Byers) and Gaten Matarazzo (Dustin Henderson) dancing to “Everybody Wants To Rule The World,” by Tears for Fears. He brought attention to the song's lyric “nothing ever lasts forever.”
“We'll be friends in the end, but 'Stranger Things' has been a big part in my life and helped me and exposed me to the world,” McLaughlin says. “It's not going to be bittersweet. It's going to be really sad.”
Sink says no one really wants to talk about the show ending.
“It's a bit of a sore topic, but I think Season 5 will definitely be an emotional ride from start to finish," she says. "And hopefully we can all be together as much as possible.”
This article originally appeared on USA TODAY: 'Stranger Things' finale: Sadie Sink and Caleb McLaughlin explain