4. The Red Wedding, Part Deux
The other scene in trailers hitherto unseen this season is Walder Frey celebrating with his two sons. It is clear now he is celebrating the return of Riverrun, which occurred in episode eight. A wider shot reveals he is dining with his family as well as the Lannister troops who aided in retaking the castle.
In a long line of the show tying up or simplifying the numerous loose ends of the books, I suspect this setting up the desired but unexpected “second Red Wedding,” this time perpetrated against the Freys themselves. As for who carries it out, I honestly haven’t figured that part out yet though in the books and show, the Brotherhood Without Banners are likely suspects, having harassed/killed the Freys endlessly since they took over. Lo and behold, like the Freys, they just popped back up after a three season absence to recruit the Hound! Coincidence??? Maybe!