Although Littlefinger failed to convince Sansa to claim the Kingdom of the North as the true born daughter of Ned and Catelyn Stark in Game of Thrones' season six finale, Westeros' master manipulator still has a few tricks up his sleeve. "Your father and brothers are gone yet here you stand," he says to Sansa in the first season seven trailer. "Last, best hope against the coming storm."
However, Lord Baelish's past may come back to haunt him, as there's still one living Stark sympathizer who knows about his betrayal of Ned in season one: Sandor "The Hound" Clegane.
After Ned discovered that Joffrey was not the son of Robert Baratheon but rather the product of Cersei Lannister's incestuous relationship with her twin brother Jaime — and therefore not the rightful heir to the Iron Throne — Littlefinger offered to help Ned stage a coup by rallying the City Watch behind him. But when Ned was arrested for treason, it was Littlefinger who held a dagger to his throat as his men were murdered around him.
At the time, the Hound was loyal to the Lannisters and was present in the throne room as Joffrey's bodyguard. However, he later developed relationships with both Sansa and Arya, offering to take Sansa home to Winterfell after deserting his Kingsguard post and traveling with Arya throughout Westeros. Arya even admitted that she had taken him off her kill list by the time she parted ways with him in the season four finale.
The Hound is currently journeying north with the Brotherhood Without Banners, which means he could cross paths with one or both — if Arya returns home — of the Stark sisters at Winterfell. If he sees Littlefinger whispering in Sansa's ear, he may be the one who finally reveals that the former Master of Coin is the reason their father was executed, prompting them to put an end to Littlefinger's scheming once and for all.
"Sansa (and everyone else in the north) never found out about Littlefinger's role in Ned Stark's arrest," wrote Reddit user Flay_the_pope following season six. "Ned Stark could still be alive and the [War of the Five Kings] may never have happened had Littlefinger not betrayed Ned in the throne room. Do you know who was in that throne room and is probably heading north? Sandor Clegane. I believe if Littlefinger, Sansa and Sandor all end up in the same room, Littlefinger will be in BIG trouble and this may be his downfall."
And if Arya is the one to do the job, this could also explain why there are photos of her with the Valryian steel dagger that Littlefinger pulled on Ned during the betrayal.
Season seven of Game of Thrones premieres July 16 at 9 p.m. on HBO.