So what is Littlefinger's play, here? Besides being creepy, I'm not sure what the end game is. He likes Sansa in a creepy way, so he's going to create major conflict between her and her unstable, assassin sister? Seems like a pretty bad plan...

I'm not sure Arya is playing Littlefinger, because that final scene with her and Sansa had no Littlefinger even there. She was full-on going after Sansa. But you could be right.

I feel like I'm missing what the characters' motivations are.