I Know Who Killed King Joffrey on Last Night’s ‘Game of Thrones’
We all know that Joffrey's "Idiot" is the guy who planted the poison -- most likely. And everyone is talking about it. He's the one who killed Joffrey. All I want to scream is, "You people are the idiots." The Idiot was only the tool. The person who killed Joffrey was a member of one of two groups. I'll put myself out on this and make the call.
Think about who'd benefit from Joffrey's death.
The people who have the most to gain is the new queen and her mother. That doesn't sit logically with me because it's too soon after the wedding. And, they're the most obvious people to benefit. Meaning, it would be a mistake for them to do that. Everyone would be looking to them.
His own mother and Jaime -- the man no one knows is his father -- have the most to lose.
See, Joffrey is not supposed to be king. He's the product of a brother and sister having sex and Jaime may have ordered the death in the context of putting down a bad dog. Jaime created something bad and it's haunted him for years. Also, if Joffrey ever found out his true lineage he'd kill his uncle/father to hide the truth.
I think that is the most likely scenario.