Quote Originally Posted by Werthead View Post
They could do. The variances between the TV show and book are relatively modest so far, but the butterfly effect means that all these small changes will gather strength and cumulatively make the TV show rather different to the books by the later seasons. Even GRRM has said he expects this to happen.
This is a common occurence when manga is adapted into anime, and happened, for example, in the first anime adaptation of Full Metal Alchemist.