hehe i like the theory that Jaime abd Cersei are actually the Bastards
For this to be possible it would have to mean that Tywin was not aware of this fact due to him not letting them be around if they werent his.
So some late night, Tywin is out doing his business running the realm as Das Hand
Aerys in some ways jealous and the fact he is a nutter takes Joanna into his bed, she becomes pregnant. To avoid Tywin going on a rampage she tells it they are his, he loves his mighty Son and his Prizecow to trade <also known as Jaime and Cersei>. Tywin only finds out the truth about these two when Joanna dies giving birth to the son of his own loins Tyrion.
So now Tywin is in a pickle, he can disown the two children he has someone grown "fond" off and let the dwarf take over, so now he in trouble. Jaime cant inherit due to him being in the KIngsguard and he wont give any legitimate heirs. Cersei cant inherite as she is a women and to be married off.
hmmmmm i written myself into a corner.
So his best choice on this day is to make sure Kevan Lannister takes over
Bah written sop much i refuse to remove it
The mad rantings of a Dane