She'll be shocked, but intrigued.

Cat stared at her husband in dumbfounded wonder. "Ned... you... this can't be serious?"

Cersei stepped forward, placing a hand on Catelyn's shoulder. "Why not? Aegon the Conqueror had two wives... Why cannot Eddard Stark, the King of Ice?" She leaned forward. "Is he not worthy of such an honor."

"Aegon... Aegon was the blood of Valyria," muttered Catelyn. "They followed different rules... different laws..."

"And Eddard is the blood of the First Men," whispered Cersei. "They follow different gods."

Catelyn turned to her husband, her blue eyes wide, looking for an answer from him.