http://insidetv.ew.com/2013/06/02/game-of-thrones-author-george-r-r-martin-why-he-wrote-the-red-wedding/
ENTERTAINMENT WEEKLY: How early in the process of writing the book series did you know you were gonna kill off Robb and Catelyn?
GEORGE R.R. MARTIN: I knew it almost from the beginning. Not the first day, but very soon. I’ve said in many interviews that I like my fiction to be unpredictable. I like there to be considerable suspense. I killed Ned in the first book and it shocked a lot of people. I killed Ned because everybody thinks he’s the hero and that, sure, he’s going to get into trouble, but then he’ll somehow get out of it. The next predictable thing is to think his eldest son is going to rise up and avenge his father. And everybody is going to expect that. So immediately [killing Robb] became the next thing I had to do.
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