Board Thread:Spoilers!/@comment-6175354-20151221210207/@comment-26443838-20151221212900

I am not sure, but maybe Robin is the connection. I mean it was teased that He has a dark secret and past.

If so, it might have something to do with Maid Marian. After all, he said in 3x21 that he would go to Hell to bring back his wife. But he made a closure and moved on.