Cersei couldn't help the quick intake of breath when she heard Jaime speak of their love. Perhaps her brain needed more oxygen to wrap her mind around it all or perhaps it was the mere idea of being able to love her brother opening, but whatever it was it felt amazing. When he stopped her she turned to look at him, her green eyes searching his. There was comfort and protection there, but love also. They were born for each other, Jaime spoke the truth and she wanted him badly, to touch him and feel him, to let him take her there. There was an intense familiarity and comfort in Jaime's touch which was something that Cersei desperately needed.
Cersei kissed her brother back, closing her eyes and wishing to deepen it, but even if their love was allowed here surely any such love was not allowed in public... at least not that she had seen. "If it is as you say and we are free to love as we might here I will be content," but if only actions were as easy as words for the next bit of information flared Cersei's temper and she pulled away from Jaime's touch.
"Noble blood?!" she exclaimed. "I wouldn't care if that child had the blood of dragons in her, I still would not welcome her into our home. She comes from traitor's blood and traitors only beget more traitors." But who or what was there for Arya to betray here? The question entered into Cersei's mind for only a moment before the next bit of information came at her.
Her anger seemed to dissipate and she reeled backwards, feeling faint. Joffrey knew and not only that, but he had found out in some mystical way and bore the name of Hill. Joffrey, her firstborn, their firstborn reduced to wear the name of bastard. No, it wasn't something Cersei could really process and she felt as though she might faint then and there. "My son," she whispered, putting a hand to her brow as she doubled over to catch her breath. Nothing could effect her quite so much as hurt coming to her family.