None book reader here….. let's break down littlefingers plan
The Lannisters have an alliance with Dorne, Highgarden, the Vale & Bolton
Littlefinger teamed with Highgarden to betray the Lannisters, kill Joffrey and kidnap Sansa. The question is, what did Littlefinger get from Highgarden in order to pull this off? We know how Highgarden benefits from this action - the crown. But kidnapping Sansa, alone, cannot be the guarantee he was provided.
I say this because, Sansa CANNOT marry her cousin publicly. This can't be done for one reason alone:
- Doing so would obviously tell the Lannisters that he was behind Joffrey's killing and launch the two sides into war. If he can't marry them publicly, then she cannot assume control and unite the North.
So I wonder if Highgarden has promised to protect Littlefinger if news surfaces that Sansa is in the Vale? This is quite peculiar because that's all but giving Littlefinger the advantage in the relationship. If he drops dime about Joffrey's death, the Lannisters kill Marg, attack Highgarden - and Littefinger never sends a single soldier outside of the Vale. Seems like a bad play from Highgarden to get the crown.
The real question then is, what signature event will Littlefinger wait for/create in order to allow Sansa to resurface? Any scenario you can think of that allows Sansa to be alive outside of Kings Landing ends up with war breaking out in that land.