[Ol Dirty Dastard]

Originally Posted by Requiem Yeah, I don't necessarily think he 'knew' they would stay. I think he had to take the chance because Karstark forced his hand. He put Rob in a bind and forced him to make a decision that any honorable man in his position would have had to think very hard about. In the end, he did what his father would have done. Granted it had severe short-term consequences, but imagine the reputation hit in the long run if he had given him a slap on the wrist? Instead, he did what he knew was right. Karstark had betrayed his trust with an emotional decision to murder two Lannister boys against the King's will. I can't really fault Rob at all for his decision. Would Karstark truly have respected Rob if he gave him a slap on the wrist? You could see the disrespect brewing immediately when he was brought in to face Rob. He acted like he knew exactly what was coming; a slap on the wrist from the pathetic king who wouldn't give him what he wanted. This is slightly similar to the Umber situation, except that Umber had the good sense to know when he was put in his place and to pay respect when it was due. Karstark had a chance to put his faith in the King and trust that when the time came, he would have his revenge where it mattered; on the battlefield. Instead, he just gave the Lannisters the upper hand by getting himself beheaded and Rob losing his army and lords. Karstark did exactly the opposite of what he intended, by being a hotheaded idiot.

Well explained