‘Stranger Things’ actor didn’t know when that did-she-or-didn’t-she moment was coming

Warning: This article contains spoilers about the Season 4 finale of “Stranger Things.”

From first kiss to temporary breakup to Season 4 finale, Lucas Sinclair and Max Mayfield have had a roller-coaster ride on “Stranger Things,” ever since Sadie Sink’s character first arrived at Hawkins Middle School at the beginning of Season 2.

But when it came to filming Max’s heart-stopping did-she-or-didn’t-she-die moment, Caleb McLaughlin, who plays Lucas,said he had no warning of what he was about to witness that day.

“I didn’t even know we were doing the death scene that day,” he told the Hollywood Reporter. “So, I just had to understand my feelings and my place in the scene. I knew my lines and what I saw prior to what was happening. I don’t really like to rehearse scenes like that because I want my natural reaction.”

“I want to be real and raw in the moment,” he continued. “So, I went off the cuff, just went for it. Of course, as we did more takes, it got better and felt more real. And it helped that [episode directors Matt and Ross Duffer] allowed me to improv and catch the energy of the scene.”

McLaughlin also revealed to THR that the improvised nature of the scene required a lot of trial-and-error to get it right, from the outpouring of tears to the exact camera angle.

“They did close-ups on me and then close-ups on Sadie and then wide angles of us together. And each time, I really had to keep the emotion of the scene. … . And we were in the cold water — such cold water — and I had to cry again. It was really exhausting, but it was great.”

And it wasn’t done at that point: Two weeks later, he said, they had to do it again to include Millie Bobby Brown’s Eleven in an alternate-reality version of the scene.

Elsewhere, the 20-year-old admitted he didn’t know the artist behind the unofficial theme song of the season — Kate Bush’s “Running Up That Hill.”

Max’s favorite song reappears frequently throughout the season, playing a key role in the story, and in turn Bush’s 1985 hit resurfaced on the Billboard Hot 100 at No. 4 more than 36 years after it was first released. The song has also wormed its way into McLaughlin’s head.

He said he didn’t know whose tune would be repeating on Max’s Walkman until Sink told him it would be Bush.

“I was like, ‘Cool. Who’s that?’” he told THR. “And she played a little bit of it. And I was like, ‘It sounds cool. She’s got a great voice.’ And now I know that song word for word.”