re: Crackpot ASOIAF Theories SPOILERS

I think the Shae being in Tywin's bed scene was put in more to demonstrate Tyrion being betrayed by Shae than about making him hate Tywin even more. He hated Tywin plenty enough already. But I think it may have taken this extreme to make him cut ties with Shae even beyond her testimony. (I wish I could remember the details of her testimony against him but it's been awhile since I read tht).

As to Tywin, you can look at it a couple different ways. He may just have wanted to nail down 100% that Shae's testimony at Tyrion's trial would not falter or be changed. So he may have wanted to keep her close and lead her to think she had a cushy gig as his ho' until he was sure he didn't need her anymore. Or it could just be that Tywin was like pretty much the vast majority of medieval style royalty and enjoyed him some strange. Heck, I'm sure almost all of the European kings were like that. With the exception of maybe a couple of ultra religious ones. And I don't really picture Tywin as being ultra religious.