So far, she has appeared in A Storm of Swords and A Feast for Crows, with many readers left disappointed that she never made an appearance in the TV adaptation.
Speaking to Entertainment Weekly, Benioff and Weiss said that there was “never really much debate” about including the character, describing her surprise appearance at the end of ASoS as “one of the best ‘holy s***’ moments in the books’.”
However, the pair explained that there were a number of factors behind the eventual decision not to include her, one of them being Martin’s forthcoming books, which they didn’t want to “spoil”.
Another reason was the character of Jon Snow, who dies and is brought back to life between seasons five and six.
“We knew we had Jon Snow’s resurrection coming up,” Benioff said. “Too many resurrections start to diminish the impact of characters dying. We wanted to keep our powder dry for that.”
Finally, with Catelyn having died during the Red Wedding, a scene widely regarded as one of Game of Thrones’ most shocking for the murder of Catelyn, Robb Stark (Richard Madden) and his wife Talisa (Oona Chaplin), Benioff and Weiss said that they didn’t want to undo Fairley’s hard work by bringing her back in a way that didn’t showcase her talent.
“Catelyn’s last moment was so fantastic, and Michelle is such a great actress, to bring her back as a zombie who doesn’t speak felt like diminishing returns,” Benioff said.