re: Crackpot ASOIAF Theories SPOILERS

I'm pretty sure it went down like this. LF and the Tyrells had planned Joffrey's death from the beginning. When LF was dispatched to try and win the Tyrell's after Renly died, I believe they made a plan to kill Joffrey off in order to arrange the Margery Tommen union. Joffrey was corrupted by his mother and they needed to remove her in order to stake their claim to the throne. LF arranged for Dontos to give her the hairnet. The QoT loosened the stone. Sansa unknowling dropped it in the goblet. It is basically untraceable to either party. Poor Sansa and Tyrion got the Shaft. By getting Tommen instead, they now have a boy that is enamored by his pretty bride and the glamour of Highgarden. The Tyrells are trying to replace the Lannisters as true rulers of the realm like the Lannisters were when Robert was alive.