Board Thread:Spoilers!/@comment-6175354-20151221210207/@comment-26159109-20151222175440

Hmcooper4 wrote: I think we may be forgetting one thing.

In order for a person to be able to summon Charon and open the portal to the UW, they have to be someone that has been the Hell and back. (confirmed in 5x10).

By that bit of foreshadowing reference, it almost has to be Rumple. The real question is... Why? What is the story here? Just because the writers want us to forget doesn't mean that David isn't one as well, but I'm sure he is not the one since they want us to forget.