• Warning: Major spoilers head for the series finale of HBO’s “Game of Thrones,” titled “The Iron Throne.”
  • Sunday’s finale finally revealed why Kit Harington cried so much at the show’s final table read.
  • In the series finale episode, Daenerys Targaryen, who is played by Emilia Clarke, looked poised to take the Iron Throne, but was killed by her lover and nephew Jon Snow, played by Harington.
  • Recalling the moment Harington read his final scene with Clarke, he told Entertainment Weekly: “I looked at Emilia and there was a moment of me realizing, ‘No, no.'”
  • Visit INSIDER’s homepage for more stories.

We finally know what made Kit Harington cry so much at the table read for the “Game of Thrones” series finale.

HBO released a trailer for its documentary about the making of “Game of Thrones,” which features behind-the-scenes footage of the cast and crew during the final season, earlier this month.

The trailer shows Kit Harington (who plays Jon Snow) crying as he reads his final scene with Emilia Clarke, who plays Daenerys Targaryen.

At the time it was not obvious what set him off – but after watching “The Iron Throne,” the show’s final episode which aired on HBO on Sunday, May 26, it’s clear why.

This is your last warning before we dive into major spoilers for the series finale of "Game of Thrones."

Read more: HBO released the first trailer for its 'Game of Thrones' documentary that shows Kit Harington crying and teases Emilia Clarke's last scene

Daenerys Targaryen and Jon Snow finale scene Game of Thrones season eight

Foto: Emilia Clarke and Kit Harington as Daenerys Targaryren and Jon Snow on "Game of Thrones."sourceHBO

In the series finale, Jon Snow kills Daenerys Targaryen after she ascends to the Iron Throne, a campaign which saw her kill thousands of innocents in the process.

Fans were upset by the death, with many feeling that Daenerys' fate was undeserved.

Whether you loved or hated the ending, as reported by INSIDER's Kim Renfro, the death actually comes very close to matching with legends found in George R.R. Martin's book series.

And it turns out Clarke and Harington had plenty of time to prepare.

Speaking to Entertainment Weekly, Clarke talked about the moment she found out about her character's fate back in October 2017.

She recalled thinking: "What, what, what, WHAT!? Because it comes out of f---king nowhere. I'm flabbergasted. Absolutely never saw that coming."

Read more: Emilia Clarke says she knew about Daenerys Targaryen's plot twist for 2 years: 'It was so hard to keep it a secret'

She said she had to make a cup of tea before reading the script.

"I cried," she said. "And I went for a walk. I walked out of the house and took my keys and phone and walked back with blisters on my feet. I didn't come back for five hours. I'm like, 'How am I going to do this?'"

She added that she called her mom and said: "I read the scripts and I don't want to tell you what happens but can you just talk me off this ledge? It really messed me up."

As luck would have it, she ended up sitting next to Harington, who deliberately hadn't yet read the script, on the flight to Belfast for the final table read.

When the cast went through the final script, Clarke said she sat across from Harington so she could "watch him compute all of this."

Read more: How that devastating 'Game of Thrones' finale death was an imperfect fulfillment of the show's biggest prophecy

When it came to their final scene together, Harington told Entertainment Weekly: "I looked at Emilia and there was a moment of me realizing, 'No, no,'" to which she nodded back, "'Yes.'"

"He was crying," Clarke said. "And then it was kind of great him not having read it."

Harington said he expected reactions to the finale to be divided.

"But if you track her story all the way back, she does some terrible things," he added.

"She crucifies people. She burns people alive. This has been building. So, we have to say to the audience: 'You're in denial about this woman as well. You knew something was wrong. You're culpable, you cheered her on.'"

Read more: Every major moment on 'Game of Thrones' that foreshadowed Daenerys Targaryen's deadly character twist

Clarke said that, ultimately, she had always thought her character would die.

"I feel very taken care of as a character in that sense. It's a very beautiful and touching ending.

"Hopefully, what you'll see in that last moment as she's dying is: There's the vulnerability - there's the little girl you met in season 1. See? She's right there. And now, she's not there anymore."

She went on: "But having said all of the things I've just said… I stand by Daenerys. I stand by her! I can't not."