Game Of Thrones: 10 Shocking Revelations From Benioff & Weiss's Q&A

3. They Started Writing For The Actors

One of the more understandable revelations (but nonetheless interesting) is that the showrunners allowed the actors in the roles to define how the show unfolded. Tailoring existing stories, and even creating new ones, to better suit the cast.

"Dan is saying that he let the actors redefined the roles, esp Maisie and they began writing for the actors, it is like the actor moved into the “house” and redecorated. He said he learned about the characters from the actors"

While this isn't anywhere near as fleshed out as it could be, it might go some way to explaining why certain characters developed in different ways to their literary counterparts. Several players became significantly more important than their role in the books, while others faded away or were written out entirely. It's one that makes sense, but will be of little comfort to everyone who really wanted to see Lady Stoneheart.