Thank you for the review, Right What Is Wrong
To be clear, Cersei's moonblood starts on Feb 1, and the feast/betrothal announcements on Feb 13. This chapter is Feb 14.
Jaime couldn't help but voice his opinion to their father. It terrified him, talking to his father always did. Jaime thought his father was a bit mad and he very much didn't like how he treated his mother, either. Still, Cersei was important enough to him that he would take any kind of yelling or beating his father had in store for him just for the chance to marry her.
"Father, may I speak with you?"
Aerys eyed his son suspiciously, "What is it? If this is about the marriage, forget it. I will not have you wait to marry until another sister is born. Your mother has not been reliable in birthing healthy ones. Nor have the wet nurses been reliable in keeping the healthy ones alive."
"It is father, but not that. I believe that Rhaegar should marry Elia, since they are closer in age. Since Cersei and I are twins, the gods would want us to marry."
Aerys laughed as he leaned back in his chair. "The gods? What gods? We are Targaryens. We answer to no gods!"
"Of course, father. But, I love Cersei, and she loves me."
"Love?" he laughed. "You foolish boy. Get out of my sight."
Jaime wasn't deterred by this, and decided to try another approach. "You always say that we have enemies everywhere. If you were to marry Princess Elia to your heir it would solidify our alliance with Dorne far more than a marriage to me would."
"I have ways of dealing with any enemies who even think to try to usurp us. You know how important it is to keep our bloodline pure. I will not have the future crown prince descend from dornish filth when there is another option!"
"What ways?" asked Jaime, concerned. He wondered if what Rhaegar had said was true. Was their father really descending further into madness?
"That's not of your concern. You will marry Elia next year. If it's any comfort, she is said to be rather frail of health, and a couple of births will only make her weaker until her body gives out. Perhaps by the time she passes, there will be another sister who you can one day look forward to marrying."
It was doubtful, Aerys' sister-wife, Rhaella had many stillbirths. Her only children to survive past infancy so far were Rhaegar, Cersei, Jaime, and five-year-old Viserys. Any even if he did have another sister it was Cersei that he wanted. Nonetheless, his father was stubborn and he could tell this subject wasn't going to go anywhere so he took his leave.