The following contains spoilers for Game of Thrones season seven.
For Game of Thrones addicts, prophecies are everything — they determine which characters we root for, how we predict future storylines, and which plot theories we actually believe. So for most fans, Cersei Lannister's prophecy isn't even a question; of course it will be fulfilled! Cersei has to die at the hands of one of her younger brothers. But many of these same fans also want Arya Stark to cross everybody who has wronged her off of that lengthy kill list, Cersei included . . . so which will actually come true?
While it seems impossible for both Cersei's prophecy and Arya's list to be fulfilled, there is one solution.
Well, according to a new theory: both. While it seems impossible for both the prophecy and the list to be fulfilled, there is one solution that could satisfy each GOT camp.
As we know, at the end of season seven, Jaime Lannister has just left Cersei in a huff of disgust. At least according to actor Nikolaj Coster-Waldau, the middle Lannister child no longer loves his sister and has left her for good. Jaime is likely headed to Winterfell to fight in the Great War . . . but first, he'll have to endure a couple of awkward reunions. Namely with the Stark children, whose family he helped destroy while irreparably injuring one of them in the process. Oh, and with Daenerys Targaryen, whose father Jaime is infamous for slaying.
While Bran Stark, who has the most reason to hate Jaime, will probably use his greensight to see the Kingslayer's redeeming qualities, the same can't be said for the rest of the folks at Winterfell. What if switching sides to fight the Night King and his horde of undead cronies isn't enough to redeem Jaime in the eyes of the North, and he is killed upon arrival?
Cersei will seek to repair her relationship with her brother, not knowing that it's actually a murderous Stark beneath Jaime's handsome face.
If Jaime is killed in the North, it would create an opportunity for Arya to take his face and head toward King's Landing, imitating Jaime in the same way that she enacts her revenge on the Freys at the beginning of season seven. See where I'm going with this?
Upon arriving in King's Landing, "Jaime" would have easy access to the Red Keep and to Cersei. Cersei, who looks stricken during her final season seven interaction with Jaime, will seek to repair her relationship with her brother, not knowing that it's actually a murderous Stark beneath Jaime's handsome face. "Jaime" would then create some sort of scenario that allows him to be alone with Cersei, then murders her, thus technically fulfilling the valonqar aspect of Cersei's prophecy while also helping Arya mark another name off her list.
Considering that Cersei's zombie henchman The Mountain is also high atop Arya's list, she might cast aside Jaime's face at this point, taking Cersei's as a way to approach and murder The Mountain. Maybe that's what The Hound means in the season seven finale when he tells his older brother, "You know who's coming for you."
So, there you have it! Cersei could technically be killed by her brother, but Arya could also complete her checklist of murderous revenge. The whole "faceless" thing is a nice skill to have, eh? We will see how things shake out in season eight!