Game of Thrones season 7, episode 5: Here's what Sansa's letter said and why it's important

Game of Thrones is no stranger to callbacks, but the one shown last night as part of season 7, episode 5 stretches aaaaall the way back to season 1, so it's understandable if you've forgotten some of the finer details. That's why we're going to help you out and break down one particular moment and its implications. But first, of course, a great big ol' SPOILER WARNING.

Now reunited with her family, Arya Stark has been catching up on everything she's missed over the past few years. While digging for some info (thanks to a bit of manipulation by Littlefinger), she comes across a letter written by her sister Sansa years earlier. And here's where we rewind back to when Ned Stark still had a head.

The letter, it turns out, was written while Ned was branded a traitor and Sansa was pressured to call her brother Robb back home. Faced with the prospect of losing her father and brother (if not her own life) and with a conniving Cersei practically forcing a quill into her hand, Sansa relented and wrote the following:

"Robb, I write to you with a heavy heart. Our good king Robert is dead, killed from wounds he took in a boar hunt. Father has been charged with treason. He conspired with Robert’s brothers against my beloved Joffrey and tried to steal his throne. The Lannisters are treating me very well and provide me with every comfort. I beg you: come to King’s Landing, swear fealty to King Joffrey and prevent any strife between the great houses of Lannister and Stark."

Robb could tell immediately that Sansa didn't mean any of what she wrote, and he ended up doing exactly the opposite of what was asked of him. A couple seasons later though, poor Robb and his men end up on the wrong side of a trap known as the "Red Wedding," with that famous line "The Lannisters send their regards."

Arya barely escaped said trap, but not before witnessing Robb's headless corpse being paraded around town. That's imagery that sticks with you, and Arya still has plenty of rage about what happened. And while she knows the Lannisters were involved with Robb's death, she doesn't know about Sansa's coercion and Cersei's hand in writing this letter. To her, it no doubt looks like Sansa (whom has become increasingly cold-hearted and untrustworthy in Arya's eyes) tried to lure Robb to his death.

And that, of course, is exactly what Littlefinger wants. Here's what showrunner Daniel Weiss said on Game of Thrones: Inside the Episode: "Arya is very used to being more clever and more stealthy, and smarter than any of the people she's up against, but she hasn't dealt with Littlefinger for a while. She gets roped into spying on somebody who's actually leading her by the nose to something that he wants her to have. He's looking for a way to prevent this sister bond from developing further because the tighter they are the more definitively he is caught on the outside of it."

"On the Sansa end of the relationship he's seen the opening and now all he needs to do is give Arya a cause to display real rage towards Sansa. And, he knows full well that with what's going on in Sansa's head with regards to Arya and how dangerous she is, when Arya starts to act dangerous, and act angry, he knows where Sansa is going to turn."

It'll be interesting to see what prevails here: familial bonds and a willingness to trust, or outsider manipulation and schemes.