I keep coming back to the idea that MRJ will be Jack from Jack and the Beanstalk. It’s very odd that the casting call for Jack has gone out, but we’ve yet to hear mention of an actor being cast for his role. It was just shortly after the casting call for Jack went out that we heard mention of MRJ joining OUaT, but the only description given to him was a “mysterious new character.” It seems like MRJ and Jack could easily be one-in-the-same.
I saw this theory on tumblr that makes a further compelling point. Remember that giant hole in the ground on the SB film set? It could be where a magic beanstalk sprouted up when magic came to town. The fairy tale has been confirmed to appear in Season 2 so it would make sense for the beanstalk to feature, especially with magic having returned to Storybrooke. The stalk itself would be CGI, but they physically made this hole.
The ground has been pushed UP not DOWN, so that means something has come out of the ground, therefore it could be the beanstalk growing.
"That’s how you know you’ve really got a home. When you leave it, there’s this feeling that you can’t shake. You just miss it." Neal Cassidy