[Buehler445]

Originally Posted by keg in kc

I thought on the TV show they set everything up pretty clearly, centered around the moment Tyrion tried to send her away (with Bronn). Basically they established just prior to that that Cersei had discovered Shae's presence. Bronn was paid off and delivered her to them rather than the ship (as basically established in Bronn's visit to Tyrion in his cell). And then Shae was paid off to testify against Tyrion. A snowball set in motion by Tyrion himself when (and how) he tried to send her away.

The books do fill in some details here which were not made clear on the show, and did kind of establish what was going on. I'm going to spoiler tag these just in case you don't want to know, although they aren't actually spoilers at all (talking about things that have already happened on the show....):

Spoiler!

Cercei gives Shae a home in a kings landing and a knight to marry in exchange for her testimony. So the motivation there is clear (she gets what she never could from Tyrion....).

And, as far as Tywin's murder goes, as Jamie helps Tyrion escape, he tells the Imp that Tysha (Tyrion's first wife - who was mentioned in season one, so i'm not sure why they left it out) had never been a whore. The whole thing had been a lie perpetrated by Tywin as a lesson. That enrages Tyrion, and leads directly to him sneaking into the tower of the hand and killing both Shae and his father. He's in a red haze at that point, basically, and seeing Shae there is the last straw.

Makes sense. Thanks. Just seemed to fit that Shae had been in on it all along. Oh well interesting theory.