This article contains spoilers for those who haven't read George R.R. Martin's A Storm of Swords, the third novel in A Song of Ice and Fire. But, since it looks like the event and/or character in question may never appear in David Benioff and Dan Weiss' Game of Thrones, reading this recent piece of news might not actually give anything away.
Well, as long as you don't plan on reading the books once the TV show finishes its seven season run. Or maybe, you simply don't care about spoilers and just want to see what all the fuss was about after the finale . Have I been clear enough? You have been warned. SPOILERS!