Board Thread:Spoilers!/@comment-6175354-20151221210207/@comment-26084266-20160130192858

I personally think the connection is that we will see in flashbacks Zelena crossing paths with Hades either before giving Dorothy the silver slippers (maybe she used the slippers previously to go to the Underworld) or after she banished Glinda to EF and gave Dorothy the slippers with her pendant.

I don't know where the timeline would cross, but I think Zelena had made a deal with Hades at some point which granted her temporary immortality if she came across death, kind of like a one shot deal hence Rumple stabbing her and turning to stone. It would explain that plot, although Glinda did claim to guard that pendant because in many ways "it now is her life", maybe there was a connection with the Oz Pendants to the underworld to grant the witches some form of safety if they came across death? Either way, I think the connection is going to show what happened to Zelena after she was stabbed by Rumple and how she was able to have her life force flee her body because the fact that she was able to cheat death was undermined in the whole Marian/Zelena storyline. I think maybe Zelena promised Hades her first born (which she probably never expected to have) in return for her life or for being given the temporary immortality during her pendant saga in case of anything. Just my thoughts. I think it'd be too far fetched for the show to throw Hades in as Zelena's baby father, but who knows with Once lol.