Most fan theories in the final days of the “Game of Thrones” series were entirely speculative — you could build a body of evidence to support an argument for them, but there was rarely anything resembling actual proof.
The one exception was the theory — and hope — that Catelyn Stark would be brought back from the dead, an event that fans of the books had spent years waiting to see. Following her death at the Red Wedding in Season 3, it was simply assumed that one of the ensuing seasons would close on the image of the Stark matriarch opening her undead eyes; this was for good reason: it happened in the books.
The third installment of Martin’s series, “A Storm of Swords,” ends with the reveal that Catelyn has been brought back to life by the Brotherhood Without Banners — whose leader, Beric Dondarrion, had been similarly resurrected. Once a warm, compassionate woman, Catelyn is now an embittered revenant, going by the name Lady Stoneheart and desiring nothing but bloody vengeance against both the Lannisters and the traitorous House Frey. With Beric having finally succumbed to death, Stoneheart has assumed leadership over the Brotherhood, which has become a twisted mockery of what it once was. It’s a pretty major occurrence that, fans figured, could never just be left out.
Ultimately, the “Game of Thrones” show omitted the entire thing. After all those seasons of expectant waiting, Catelyn never came back. Instead, Beric somehow lasted all the way to Season 8, and the Freys were eventually massacred by Catelyn’s daughter, Arya.