Re: G.o.T. who killed the king ?
This whole thread qualifies as a spoiler lol.
Great theory with the necklace though. If Olenna didn't do it herself, she definitely had a strong hand in it. Those eyes don't lie! I would think their family has plenty of reasons to want Joffrey dead. I don't think having Margaery marry Joffrey was ever about her being queen, just a way to get this done. Feels like it was planned out for a long time. Will be interesting to see the reason(s) why.
People assume that time is a strict progression of cause and effect, but actually from a non-linear non-subjective viewpoint it's more like a big ball of wibbly wobbly timey wimey...stuff.