Y'all.
I'm listening to the audio books for the first time, but I've seen the show many, many times. I'm at the part in the audio books for Storm of Swords where Catelyn and Rob are talking about Rob's heir and bringing Jon back from the wall to legitimizing him (Chapter 45, Catelyn, 24:20). Catelyn is trying to talk Rob out of making Jon his heir when she says:
> "I know you trust Jon. But can you trust his sons? Or their sons? The black fire pretenders troubled the Targaryens for five generations until Barriston the Bold slew the last of them on the step stones. If you make Jon legitimate, there is no way to turn him bastard again."__
__HOW DOES CAT KNOW JON IS A TARGARYEN????__

