This pivotal 'Game of Thrones' scene may have just disproved a popular fan theory

Warning: Spoilers ahead for Sunday's "Game of Thrones" episode.

The fourth episode of "Game of Thrones" season six began with an emotionally charged reunion between Jon Snow and Sansa Stark. After settling into each others' presence, Sansa launched into a pitch for the two of them to retake Winterfell by attacking the Boltons.

At first, Jon was adamant about not fighting anymore. He's had enough killing for one lifetime. But by the end of the episode, he had a change of heart thanks to a gruesome letter written by Ramsay Bolton. 

This letter arriving to Castle Black is a storyline taken directly from the books. But, naturally, things on the show have played out a little differently. Let's take a look at the significance of what many call the Pink Letter.

We'll start with the books. In George R.R. Martin's fifth "A Song of Ice and Fire" installment, "A Dance with Dragons," Jon Snow receives the Pink Letter before he is assassinated by his own men. There are other significant differences too.

Mance Rayder was not dead in the books — instead he was planted at Winterfell by Jon to rescue his "sister." A girl named Jeyne Poole was being passed for Arya Stark (neither Arya or Sansa are near Winterfell in the books). Jeyne was married to Ramsay, and word spread in the North that the Bolton bastard had married Arya. Jon doesn't realize the girl isn't really his sister.

So. Jon is Lord Commander, he's let the wildlings through the wall and now he's learned that Arya is at Winterfell with Ramsay Bolton, and he sent Mance Rayder to retrieve her. Also worth noting is that Stannis has not yet attacked Winterfell in the books. The last time book readers saw him he was about to start a siege outside the castle walls.

Here's what the letter says in the books:

Your false king is dead, bastard. He and all his host were smashed in seven days of battle. I have his magic sword. Tell his red whore.

Your false king's friends are dead. Their heads upon the walls of Winterfell. Come see them, bastard. Your false king lied, and so did you. You told the world you burned the King-Beyond-the-Wall. Instead you sent him to Winterfell to steal my bride from me. 

I will have my bride back. If you want Mance Rayder back, come and get him. I have him in a cage for all the north to see, proof of your lies. The cage is cold, but I have made him a warm cloak from the skins of the six whore who came with him to Winterfell. 

I want my bride back. I want the false king's queen. I want his daughter and his red witch. I want his wildling princess. I want his little prince, the wildling babe. And I want my Reek. Send them to me, bastard, and I will not trouble you or your black crows. Keep them from me, and I will cut out your bastard's heart and eat it. 

Ramsay Bolton,
Trueborn Lord of Winterfell

Hoo boy. A lot to unpack there. The letter clearly states that the Boltons have defeated Stannis' army. Ramsay also says he imprisoned Mance Rayder, and now has a hostage request list which includes Melisandre, Selyse and Shireen Baratheon (who are at Castle Black in the books), along with Mance's wildling wife Val and their baby. Plus, Reek/Theon has escaped Winterfell and taken Jeyne with him (Ramsay's bride). 

But here's the thing: Book readers have long speculated that the letter was not written by Ramsay, and the stated events are therefore unconfirmed. There are a number of hypothetical letter writers, including Mance Rayder himself.

Regardless of who wrote it in the books, the Pink Letter is Jon Snow's motivation for leaving Castle Black to respond to the threat. In the books, this is why several Night's Watch men stab Jon. Not just because of the wildlings, but because he was about to break his vows and ride south to engage in warfare with Ramsay. 

"A Dance with Dragons" ends shortly after the Pink Letter and Jon's assassination chapter. We don't get another point-of-view written in the North, so there's no way for book readers to know for certain that Ramsay has already defeated Stannis, or captured Mance. 

This brings us to the show's version of this letter. 

First off, and most importantly, the letter is unarguably written by Ramsay Bolton. We watch as a Bolton rider arrives to Castle Black, with a wax-sealed letter bearing the Bolton sigil (not just a "smear of pink wax" as it's described in the books). 

Plus it's written after Jon is assassinated (and resurrected) and after viewers watched Stannis lose the battle at Winterfell. Sansa is Ramsay's actual bride in the show, and Mance Rayder is dead. 

Here's what the show version of the letter read: 

To the traitor and bastard Jon Snow

You allowed thousands of wildlings past the Wall. You have betrayed your own kind, you have betrayed the North. Winterfell is mine, bastard, come and see. Your brother Rickon is in my dungeon. His direwolf’s skin is on my floor, come and see.

I want my bride back. Send her to me, bastard, and I will not trouble you or your wildling lovers. Keep her from me, and I will ride north and slaughter every wildling man, woman, and babe living under your protection. You will watch as I skin them living. You will watch as my soldiers take turns raping your sister. You will watch as my dogs devour your wild little brother. Then I will spoon your eyes from their sockets and let my dogs do the rest. Come and see.

Ramsay Bolton Lord of Winterfell, and Warden of the North.

In the show canon at least, writers David Benioff and D.B. Weiss have done away with any ambiguity about the author of the letter. In a season six teaser, we heard Ramsay say "Winterfell is mine, come and see"— clearly reading from this letter script. Listen below:

And with Mance dead, there's no character in Winterfell who knows all the information contained in that letter and has motivation to impersonate Ramsay. Some people thought Sansa could have crafted the letter, since a fight against the Boltons is what she wants and this letter motivated Jon to agree. But how could Sansa possibly know about Rickon? 

Based on behind-the-scenes interviews from Benioff and Weiss, we know they consult with Martin on key plot points. If they've spoken with him about the letter, the show may have just proved several fan theories wrong. If not, book readers have more mystery to look forward to in the next installment, "The Winds of Winter."

One this is for certain — Jon and Sansa are headed south together on the show. Their plan is to visit the other northern houses previously sworn to House Stark, and hope they can gather a force large enough to match Ramsay Bolton in the battlefield. Snowbowl — or the Battle of the Bastards — is coming. 

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