Are you really asking?



If you're ready for potential spoilers,



Lady Stoneheart makes an excellent storyline in the books. Catelyn is resurrected after the Red Wedding by Beric and Thoros, and becomes leader of their gang. Really she should have been in the show by now if they are going to include her... but who knows. They seem to be changing every single storyline to the point that I can't see how the books and TV show will ever lead to the same conclusions.