This post contains spoilers for Season 7, Episode 4.
And WHAT AN EPISODE it was. There's so much to unpack, so let's dive in...
1. There was a lot of subtext in the scene where Littlefinger gives Bran the dagger that was meant to kill him in Season 1.
We saw this dagger in the promo shots for Season 7, and also in an illustration in the first episode, so we knew it'd be popping up in a big way. Here, Bran asks Littlefinger, "Do you know who this belongs to?" And Littlefinger replies, "No... that very question started the War of the Five Kings."
Part of this is true, and part of this is a big fat lie. A quick reminder of what really happened...
As Littlefinger mentions, the dagger was used in an assassination attempt on Bran after his fall, which Catelyn fiercely fights off.
It's this assassination attempt that clues the Starks in that Bran's fall was no accident. The valuable blade in particular tells them that someone very rich and important wants Bran dead.
It's this information that causes Cat to leave Winterfell (never to return, sob) and travel to King's Landing to tell Ned something is up. There, she meets with Varys and Littlefinger, and Littlefinger tells her the blade is his – or was, until he lost it to Tyrion Lannister in a bet.
It's THIS information which causes Catelyn to later arrest Tyrion at the Inn at the Crossroads, which causes Jaime to attack Ned, which causes Robb to go to war... so yeah, Littlefinger is spot on in the latest episode when he says this blade started the War of the Five Kings.
But he leaves out the part where he was probably lying about Tyrion owning the dagger, and that it was Littlefinger himself that used it to trigger the war. We all know he had already deliberately created chaos (he had Lysa Arryn murder her husband Jon, which caused Ned to investigate and discover the truth about Cersei and Jaime), and there's a very, very good chance the attempt on Bran's life was his doing to further pit the Starks and Lannisters against each other. He wanted power, and chaos was his ladder to reaching it. Speaking of which...
2. When Bran says "chaos is a ladder", he's referencing a famous speech Littlefinger delivered to Varys in Season 3, basically describing his whole game plan of using chaos to grow more powerful.
There's a reason Littlefinger is SHOOK at this statement. It's Bran's way of telling him he is onto him. He's SEEN him. He knows how he works, and he also probably knows – or will know very soon – the part Littlefinger played in starting the war and betraying Ned. Which makes Bran's decision to later give the dagger to Arya, his vengeful badass assassin sister, VERY interesting...
3. Speaking of Arya, the scene of her arriving at Winterfell is a throwback to her being stopped at the gates of the Red Keep back in Season 1.
It's interesting that in this scene, Arya mentions Ser Rodrick and Maester Luwin, who as we know are both long dead. It shows just how out of the loop Arya has been.
4. Sansa and Arya's reunion is as emotional as we expected it would be – especially because it takes places in front of the statue of Ned Stark. Fitting, considering the last time they were together, he was there.
The girls were the last of Ned's kids to see him alive, having been the only ones to travel with him to King's Landing in Season 1.
5. Meanwhile, Sansa acknowledges that Arya is Jon's favourite sibling (and actually makes Arya smile).
Arya and Jon were particularly close, as they both felt like outsiders in the family. If Sansa and Jon's reunion was emotional, and they never even liked each other that much before, just imagine what Jon and Arya's will be like.
Here's hoping that line about his heart stopping at that moment isn't foreshadowing anything... (Although technically, is his heart still beating at this point? George R.R. Martin suggests not, but the show may be different.)