Catelyn looked at Ned, the words that Petyr had just uttered had utterly horrified her and from the look on Ned's face, she knew that he felt the same. Just what had they gotten themselves into?
"So, the Crown Prince tried to have his sister murdered, thinking that by doing so he was removing a threat to his chances of inheriting the throne." Catelyn said. "That tells me two things. Firstly, he is an idiot. The succession has been guaranteed as father to son since the time of the Dance of Dragons. Secondly, it tells me that he is far too unstable to make a good husband or King."
Ned nodded, Catelyn took his hand and squeezed it knowing that he would be feeling incredibly guilty, given he had accepted Robert's offer of a betrothal.
The thought came to her, if Joffrey was capable of doing something like that to his own sister, what would he have done or would he be doing to Sansa? She looked at Ned and asked softly. "Have you noticed anything amiss with Sansa?"
At first she thought Ned was going to shake his head and she was going to breathe easily, but then he said. "I didn't think anything of it at first, but at the tourney she was awfully quiet. And she kept shooting looks at Arya and Bran. I thought it was just a normal child's quarrel but now I wonder if it might be something else."
"What do you mean?" Catelyn asked wondering how a possible quarrel between their children had anything to do with Joffrey.
"Well before we entered the stands for the tourney, Arya said something to Sansa and I only caught the tailend of it, but I heard Joffrey's name and Sansa hissing at Arya in a way to keep quiet. You know like when they were babes and there was a secret they were sharing?" Ned replied.
"I do." Catelyn said, that had been when they'd both been very very small, before Sansa had changed into the perfect little lady.
"I think something may be going on." Ned said then. "Indeed, I think with what we now know, we cannot assume that everything is fine."
"Has there been someone from our household there to walk with them when they've been together?" She asked.
Ned knew she was referring to Joffrey and Sansa for something like horror crossed his eyes. "Septa Mordane for a time, but then Robert said that he trusted the Hound and Ser Meryn Trant to oversee things and keep things proper. And I didn't want to insult him by saying otherwise."
Catelyn wanted to groan, damn Ned's honour! "So, it is possible something could have happened?"
"Ser Meryn would have intervened if Joffrey tried anything." Petyr said then.
Catelyn looked at him and asked. "How do you know?"
"He and I knew one another for some time when he was younger. And he remains a good friend. He would never allow a young woman to be hurt. Even by the Crown Prince." Petyr said.
"But there is a chance that the Crown Prince might still try to hurt her." Catelyn said. "Especially when he learns that his attempt on Myrcella failed."
"I will get Robert to call off the betrothal." Ned said then. "I do not want our daughter marrying a monster."
"You can't do it just like that." Catelyn said. "You need to provide evidence of the crimes that we're alleging he committed. We have the letter and the dagger, but we need decisive proof that he paid the man to kill Myrcella."
"How will we get those?" Ned asked.
Catelyn was about to say she didn't know when she remembered the paper with a seal on it that Myrcella had handed to her before she'd departed. She reached into her bag and pulled it out. She placed it on the table and said. "This has the Lannister seal on it and words written in a style that Myrcella says is Joffrey's."
Ned picked it up and read it, and then handed it to Petyr. She expected everyone to agree that this was enough, but Petyr surprised her by saying. "You can't end the betrothal just like that."
"Why not?" Ned demanded. "The boy tried to kill his sister and he will try something on my daughter. I do not want that."
"If you do that, then you will play right into the Queen's hands." Petry said.
"What do you mean?" Catelyn asked. "How will this give the Queen what she wants?"
"She was the one who recommended the betrothal between Joffrey and Sansa. Originally the King just wanted Myrcella married to your son. But she suggested it and I think she did it knowing that Joffrey might do something. She wants to destroy whatever influence you have over Robert, and this is exactly how you do that." Petyr said.
"How?" Ned asked.
Catelyn understood what Petyr was saying. "We go to him with this, Robert won't want to believe it. He'll think this is some ploy, or some misunderstanding. He'll blame us for not ensuring his daughter's safety and think that we're blaming his son to try and cover it up." She saw that Ned was about to protest that, but she held a hand up. "He might not want to do it, but it'll be instinctual. He won't want to believe his son is a monster, what parent would?."
"So, what do we do?" Ned asked sounding helpless.
She looked at Ned and then at Petyr and then back at Ned and decided to take the plunge. "We need to find decisive proof that she had a hand in Jon Arryn's death."