I think that the Stranger is the Cheshire Cat. He sort of talks in riddles and in a roundabout way, never giving Emma or Henry a straightforward answer. Also, someone mentioned that he wears a lot of pink and purple in his scenes. I correlated this to my theory and Disney’s version of the Cheshire Cat is pink and purple!
I’m really interested in this whole Wonderland thing and I’m looking forward to where the writers are going with this. There’s a thread on it here