All of these are very plausible, and possible theories, but again, there are thousands, maybe tens of thousands of threads at the fan sites for ASOIAF and GoT regarding this, as it's one of the most discussed mysteries of the book. "Ponderous" - that's an excellent adjective to describe the books really, and they are very lengthy, and also IMO they are greater than the sum of their parts, making them even MORE complex.
Sir Dontos its been established (at least it's been agreed by most that it's been established) was working for Baelish, and although he was an integral part of helping Sansa escape, most agree that based on what GRRM wrote, was not the one who dropped the "strangler" in the wine. There is much in the books that does in fact point to the necklace (a hairnet in the books) Sansa wore, "moonstone" gems, having been made up of disolvable "strangler" poison pellets, not stones. Ser Dontos's character was given a little more of an arc in this episode, as this is the end of the entire Dontos line in both book and TV - it was his ancestors that kidnapped the "mad king" before he was "mad", and it was Ser Barristan who rescued said king, and killed many of the Dontos's to do so. The mad king ordered the entire family executed in his first real fit of madness, but Barristan argued to save the life of the last infant son, which was Ser Dontos. So, even though it's such a small role and character, Ser Dontos is a very important part of the whole shtick of the mad king. This little bit just goes to show how impossibly complex the entire story is, as this isn't really talked about much, being only a paragraph in a single book of the series.
Anyhow, back on topic -" Maester Ballabar and Maester Frenken confirm at Tyrion’s trial that a throat-constricting poison was used to kill Joffrey. In the series thus far, we only know of one such poison...the Strangler. On page 20 on A Clash of Kings, Maester Cressen makes the Strangler out of crystals strikingly similar to those on Sansa’s hairnet--small and colored deep purple. It comes from a leaf grown near Asshai. And, coincidentally, on page 914, Dontos gives Sansa the hairnet and says the crystals are from Asshai.
So it seems the Strangler was the weapon used. But did Olenna use it? It seems quite likely. On page 672 of A Storm of Swords, Olenna does come and straighten Sansa’s hairnet, giving her a prime opportunity to grab a crystal. And she does...on 686, Sansa notes that one crystal is missing from her hairnet. And Olenna certainly had a chance to drop in it Joffrey’s drink...on page 681, she comes tottering up with Margaery to talk while Tyrion is pouring Joffrey’s wine.
Just as one last confirmation, we have a third-party who also states it was the Strangler in Sansa’s hairnet that killed Joffrey...though not so directly. As the Ghost of High Heart prophecizes on page 491:
“I dreamt of a maid at a feast with purple serpents in her hair, venom dripping from their fangs...”
The dream matches Joffrey’s murder exactly.
I pieced this together from a couple different discussions on various fan sites.
Also:
Breaking Bad - the index you ask for is coming, I mentioned in the thread already a couple of times, "A World of ASOIAF" is going to be out this year, written from the perspective of a Maestor of the Citidel recording a complete history of all things known in the world of Westeros, Essos, and beyond. You should be able to look up everything and anything there, sort of an Encyclopedia Westeros.
Regarding Baelish/Sansa - in the most recent book, Petyr has made plays already to bring Sansa into his fold, and it's widely agreed the moves he's making in this regard are to help him claim the North in her name, either through he himself, or some vassal he marries her off to. It's a really interesting political angle to the whole story.
