re: Game of Thrones S4:E2:"The Lion and the Rose", HODORS ONLY (no book readers)

Sansa was indeed the only one onscreen with her hand over the cup, right? I'm pretty sure this poison is the same that killed maester cressen and when he poisoned his wine, he let it sit there for a moment before trying to trick Melisandre into drinking it with him. Maybe there is a fermentation period for the poison to activate, thus explaining the time between her hand over the cup and Joffrey beginning to choke.

Old lady Tyrell fondles Sansa's necklace then the next scene is showing a missing gem from the necklace:



Maybe the old lady was fondling her necklace because she noticed the missing gem instead of her taking it. Sansa would be the culprit and she obviously has a world of motive. More than any character. Joffrey made her life miserable, ordered Ned's execution, had Lady killed, and by extension Robb killed as well.

If she did do it, she somehow found out about the poison in the necklace and just took the opportunity when she was able to pick up Joffrey's cup (she didn't plan how everything played out).

This would all include the fool helping as well. He rescued her at the end because maybe she was relishing his death or just stunned at what she helped do.

This would be null and void if it can be proven if the gem was on her necklace before old lady Tyrell came up to her (I don't remember). There's still some things that wouldn't make sense to us right now, but interesting nonetheless.