Board Thread:Spoilers!/@comment-25926288-20160713182420/@comment-27060727-20160714042612

My early guess is that it could be an official Jekyll/Hyde centric with backstory. Which would probably include Rumple since Hyde wanted to kill them for insinuating that they knew him back in the LoUS. (Did Rumple know Jekyll before the split....?)  If we're talking medicine and potions, then that definitely sounds like it to me.