I keep seeing people mention this, but we don't even see that in the book except in a Dany vision in book 2. I seriously doubt we will see anything of the sort.
Though I do look forward to all the people who will complain how the RW was "ruined" because they didn't see something that wasn't even in the book.
Actually, it really does happen in the books. Technically, yes, the reader doesnt directly see Grey Wind's head on Robbs body, but there are numerous characters saying that it happened. Salladhor Saan tells it to davos/stannis for instance.
Edit: Also, the reader never hears about where they buried Robbs body, or witnesses grey wind get killed. Is he still alive omg?! Did Grey wind get away and we may have Un-Robb around?!
Ok last edit I swear, #2: Pulled this from the wiki, I think I may have slipped this bit in AFFC, Jamie VII:
Jaime Lannister asks Edwyn Frey what happened to Raynald during the Red Wedding. Edwyn reveals that Raynald, the "knight of seashells", freed Grey Wind from his chains when several Frey men-at-arms tried to kill the direwolf. However, while doing so Raynald was hit by several crossbow quarrels and fell into the river. Edwyn tells Jaime that Raynald's body was not specifically found amongst a thousand corpses afterward, but his trail of blood led to the river's steps.
Pretty interesting IMO, makes me wonder.