Spoilers ahead for Game of Thrones season 7, episode 5, “Eastwatch”

As if we needed further proof that season 7 of Game of Thrones is all about callbacks to the show’s earliest season, the latest episode, “Eastwatch,” ended with Arya getting her hands on yet another blast from the past. While spying on Littlefinger, she saw him talking to various people at Winterfell before receiving a note pulled out of from Maester Luwin’s obsessively kept archives. He confirms the note is the only copy in Winterfell, then hides it in his room. Arya breaks in and steals the note — but Littlefinger is aware of her spying, and has clearly set her up to find it. From around the corner, he watches to be sure she’s gotten the message. So what is he feeding her in their spy vs. spy game, and why?

Here’s what the note actually says. You can read much of this on-screen:

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. Your faithful sister, Sansa

Game of Thrones historians might remember that back in “The Pointy End,” episode 8 of season 1, Sansa Stark was in King’s Landing, waiting to marry the vile Joffrey Baratheon, when her father Ned was arrested for plotting against him. (The details of that plot, involving Robert’s will, are laid out in the previous episode, “You Win or You Die.”) Joffrey’s mother Cersei leaned on Sansa to prove her loyalty by writing to Robb Stark in the North, urging him to bend the knee to Joffrey. Here’s that scene. Note that Littlefinger is here, playing good cop to Grand Maester Pycelle’s bad cop and Cersei’s slimy cop. (Varys just kind of hangs back and doesn’t much cop at all.)

So Littlefinger is certainly aware that this raven letter was written and sent to Winterfell by a much younger, more naïve Sansa. (Aw, just look at wee baby Sophie Turner here!) Once again, he’s pulling in a season 1 prop to try to manipulate the Starks — exactly as he did last week, by trying to buy Bran’s friendship with the knife that nearly killed him.

And here’s the follow-up scene, where Robb has Sansa’s raven dispatch in hand, and shows it to his mother, Catelyn. She immediately intuits that the letter is Cersei’s doing, not Sansa’s, and that Robb should ignore its contents. He should instead worry solely about its meaning — that Sansa (and, she presumes, Arya) are under Lannister control, and will die along with Ned if anything goes wrong. It’s unclear whether the letter was meant more to lure Robb into a trap or to force his loyalty, but it didn’t work in either case — he rallied the North against the Lannisters, and set up for an ill-fated war. We probably all remember the wedding that ended that particular ploy.

So why does Littlefinger want Arya to see that raven letter? Here’s what writer and showrunner D.B. Weiss says about this subplot in the post-episode making-of featurette:

[Littlefinger is] looking for a way to prevent this sister bond from developing further, because the tighter that bond is, 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 cause to display real rage toward Sansa… 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’s going to turn.

As I said in last week’s rundown of significant moments from episode 4, “The Spoils of War,” it was just a matter of time until Littlefinger started undermining Sansa, trying to chip away at her support in hopes of leaving her in a position where she has to come to him for help again. His plots seem to have shrunk from “control the kingdom” to “get the girl,” which is understandable given his obsession with both Sansa and her mother before her, but is also petty, manipulative, and creepy on a level he’s been maintaining for a couple of seasons now. So by trying to make Arya see Sansa as weak-willed, easily swayed, and even emotionally loyal to the Lannisters instead of her own family, he’s trying to drive a wedge between them. Arya was already questioning Sansa’s actions as regent in the North; now she has another reason to not fully trust her. We know as of this scene that Littlefinger seems to be one step ahead of Arya in their spy vs. spy game. Next, we get to find out whether she’s one step ahead of him, and whether she’s going to recognize this as the cheap ploy it is.