Jon Snow’s true heritage on “Game of Thrones” is one of the biggest pop culture mysteries of the decade.

In the Season 8 premiere, when Jon (Kit Harington) finally found out the bombshell that his real parents are Lyanna Stark and Rhaegar Targaryen (which makes him the true heir to the Iron Throne), you might have been anticipating that scene for more than 10 long years.

After all, Jon first asked Ned Stark (Sean Bean) about his mother when Season 1 aired way back in 2011. If you read the the first book in George R.R. Martin’s series when it first came out in 1996, you’d been anticipating it for over two decades.

What in Westeros is that kind of pressure like for a writer? Dave Hill, who penned the Season 8 premiere, “Winterfell,” tells the Post.

Tell me about how you prepared to write the scene in the crypts, where Sam (John Bradley) finally tells Jon the truth about his parents. Did you feel a lot of pressure, since some fans have been anticipating this for over a decade?

There’s always a lot of pressure writing “GoT” — not because of the fandom, but because your words have to pass muster with David Benioff and DB Weiss, genius writers at the top of their game. To deal with that … mostly I drank.

This scene was trickier than many because Sam is conveying information that we the audience already know, and that Jon has to hear pretty much in its entirety to get the full effect — no elision can be had, we can’t cut out of it as Sam starts to tell Jon. We’ve set it up for seasons now and we have to watch it play out in real-time.

But it’s tough to balance so much necessary exposition and rehashing (for the audience) with the emotional charge that makes the moment actually land with the audience. Luckily for me, John Bradley and Kit Harington could perform the words of a phonebook, and David Nutter would win an Emmy for directing it.

Was it always going to be an emotional conversation between Sam and Jon, or was the first idea different, and you eventually landed on the scene as it is?

I don’t know how you tell someone his entire life has been a lie — his father was never his father, he’s the rightful king of a continent, and he’s in love with his aunt to whom he’s now a rival — without it being emotional. The trick is getting at all this without feeling like you’re plowing through a laundry list, and without it getting comical. Though I’d love the Monty Python version of this, too.

We’ve been writing these characters and show for years so we’re all well attuned to their voices and the show’s tone. I do remember that the gag of Sam tripping in the dark came in the second or third draft, because it was such a heavy scene that a little comedy at the top felt nice.

And finally, what can you tell us about the spiral the White Walkers create with Ned Umber’s body and severed arms? This pattern has appeared a lot on the show.

As we saw with Bran and the Three-Eyed Raven, the spiral pattern was sacred to the Children of the Forest, who created the Night King by sacrificing a captured man in a spiral “henge of stones.” The Night King then adopted the symbol as a sort of blasphemy, like Satan with the upside-down cross.

“Game of Thrones” Season 8 airs Sunday nights at 9 pm on HBO.