Corrected entry: In a show about zombies, dragons and magic, Littlefinger's survival is the least believable thing. He fell into the hands of the likes of Catelyn, Renly and even Cersei, but they always spared him because of paltry reasons. By season 6 he's practically daring anyone to kill him, but they never do. Sansa, Brienne and Jon Snow were all itching to kill him, but they always stopped for no reason. This is a poor and artificial way of prolonging drama.
Correction: Littlefinger is extremely wealthy and resourceful and has spent the entirety of the show (and even before the start of it) orchestrating events behind the scenes that make him more and more powerful, including the murders of Jon Arryn and Joffrey. Characters aren't in a position to straight up kill him because he controls the Vale army and has influence over Robyn Arryn. It isn't until his betrayal of Ned and Catelyn is finally revealed that the Vale army and the Lords of the Eyrie no longer have his back, which gives Sansa and Arya a reason to execute him without fear of reprisal.
Littlefinger only told Sansa about the Knights of the Vale after she had faltered again in her promise to kill him. That's just terrible negotiation. He's not allowed to die until the writers say so.
He told her his army would aid her. That doesn't mean only she knows he has the army. It's undoubtedly known by the Lords and Ladies across Westeros that Littlefinger married Lysa Arryn and became the de facto Lord Regent and Protector of the Vale after Lysa's death. And saying he's not allowed to die until the writers say so isn't even a valid argument. Every fictional character that dies does so when the writers say so.
Correction: Just because the powers that be don't like or trust Littlefinger doesn't mean they don't think he is useful for their own goals. They try and include him in their own schemes, but he played the game of thrones better than they did.
Correction: That's just your opinion, not a stupidity in the show.
lionhead