This is going to be a spoiler-filled examination of the HBO program 'Game of Thrones.' If you wish to avoid spoilers about this series, please come back to this when you're caught up.
And now, a spoiler-preventing buffer image, courtesy of gameofthrones.net
OK, on with the show.
By killing Walder Frey, Arya Stark may have single-handedly paved the way for the reunification of the Seven Kingdoms of Westeros. Her infiltration of the Twins and subsequent murder of the last of the architects of the Red Wedding has opened up a power vacuum in the Riverlands at a very important time in Westeros.
In order for the following theory to come to pass, a couple of things need to happen first, and we cannot be absolutely sure that they will. However, we will be preceding with this discussion as if we are certain that these events will come to pass in Season 7.
Firstly: The death of Lord Frey as well as his sons Lothar Frey and Black Walder Rivers (who had been serving as his chief lieutenants) would have to lead to House Frey being unable to maintain control of the Riverlands. Their familial decapitation would have to drive them out of the Game, at least for a while.
Secondly: Arya will need to free Edmure Tully from the Frey dungeons so that the Tullys will be able to reinstate their ownership of Riverrun. Since Jamie Lannister orchestrated their peaceful surrender a few episodes back, the Tullys still have their military intact. This makes Edmure a force to be reckoned with in Westeros.
(Side note: it’s really too bad that the Blackfish did not flee/was killed, as only a short time later he would have had the opportunity to the command of the armies of the Riverlands once more.)
If both of these possibilities are born out, then we have a reinstated Lord of Riverrun (Edmure) who is the uncle to several important young people in the ruling houses of Westeros. Edmure’s sister Catelyn was the mother of the three remaining children of Ned Stark, Sansa, Bran, and Arya (to whom he would be personally indebted to for his position.) Edmure’s other sister, Lysa, was the mother of Robert Arryn (a.k.a. “Sweetrobbin”) the current Lord of the Vale, for whom Littlefinger is acting as regent.
These connections make it likely that Lord Edmure could be persuaded to add the Tully armies to those of the Free Folk, the Northerners, and the Knights of the Vale (and presumably what remains of the Night’s Watch, as well) under the command of the new King in the North, Jon Snow. Jon’s northern coalition would therefore be one of the three great military powers in Westeros at the beginning of Season 7.
The second major power is the Lannister army. Though Cersei Lannister sits on the Iron Throne, she and the other Westerlanders stand completely alone, as all of their former allies have either been destroyed or have turned against them.
The third power is the new alliance cemented in the finale: Olenna Tyrell of Highgarden & Ellaria Sand of Dorne (and Yara Greyjoy with her Ironborn) will be joining with Daenerys when she arrives from Essos to reclaim her birthright. These Westerosi forces will unite with the Unsullied & the Dothraki hordes to form what is likely the largest fighting force in the world.
So with these three seemingly opposing factions poised to do battle in Season 7, how do we get to a united Westeros? The answer can be found in the scene in the finale of Season 6 at the Tower of Joy, in which we finally learn the true parentage of Jon Snow. He is in fact not the son of Ned Stark, but of Ned’s sister, Lyanna, and Rhaegar Targaryen (as many fans have speculated for years). Since Rhaegar was the older brother of Daenerys, this makes her and Jon aunt and nephew to each other.
(Side note: since we now know that Jon was born at the Tower of Joy in Dorne, shouldn’t that make him “Jon Sand” rather than “Jon Snow” as per Westerosi bastard-naming conventions?)
As we’ve seen again and again in Game of Thrones, being family does not necessarily make people natural allies. However, in Cersei Lannister, Jon and Dany have a common enemy, not to mention the greater enemy beyond the Wall. If these two can form a partnership, they can help each other defeat the remaining villains in Westeros.
Additionally, if our new Targeryen-led alliance-of-alliances does succeed in defeating Cersei Lannister (and we have every reason to believe that Jamie would die by her side) then the newly-named Hand of the Queen becomes the Lannister with the strongest claim to Casterly Rock. If Tyrion does claim that Lordship, then the Westerlands would be brought into Daenerys’s camp as well.
The only other high-born Lannister that the show has featured are Tywin’s brother Kevan, who was serving as Tommen’s Hand of the King, and Kevan son Lancel, who had become a member of the Faith Militant. Both perished in a flash of green fire when the Sept of Baelor was destroyed.
So there is a fairly straightforward series of events that could lead to Daenerys and Jon, both of House Targaryen, having command over the entire Seven Kingdoms of Westeros — and it would be all thanks to Arya Stark.
Arya’s (alarmingly casual) murder of a 90-something lech has set the stage for the final battle of the entire Game of Thrones series. The only question that remains is whether the Dragons will be enough to defeat the Dead.