Board Thread:Spoilers!/@comment-6175354-20140420035659/@comment-24667994-20140423034427

I think "It's Not Easy Being Green" really cements the fact that the dark curse needs to be cast by a magic user. Otherwise, Rumple would have no motivation for teaching Regina magic, nor honing Zelena's skills (to pay the billz). In fact I would go futher to say that the episode intimates you not only have to be a magic user but a very good one to cast the curse. Consider that the previous two castings of the dark curse were performed by powerful magic users (Regina and Peter Pan). If this is the case then I have doubts that Aurora casts the new curse as she's never been shown to be a magic user. That would also seem to rule out Hook, Charming, Belle, so many others. It really seems to narrow things down.

As others have said, the thing Regina loves most is Henry so she can't have cast it--Herny still being alive and all. Zelena had control of Rumple and may have compelled him to cast the curse, but the thing Rumple loves most is his son and/or Belle. Neal was inside of him and Belle is still alive, which I think rules him out as well.

Magic users unaccounted for are the Blue Fairy and Glinda. And I have no idea what either of these characters love the most.

Of course, all this being said, it could be that I'm wrong about the curse needing to be cast by a magic user. But if I am, then I will be dissapointed, because then "It's Not Easy Being Green" doesn't make much sense.