Board Thread:General Discussion/@comment-25926288-20170320124216/@comment-24674051-20170322041742

That's an interesting theory, and it maybe even explains Rumple's sudden (at least I thought it was sudden) move to kill Zoso with the Dagger, when the original intent was to simply free Zoso from the control of the Duke.

Rumple, from what was seen, resisted using the Dagger and the Black Magic, except when he used his power first protect Bae, and then to defeat the Ogres, at least at first. He was not going to use it against Beowulf until Bae commanded him, at which point he had not choice (the truth that he told Bae later).

We saw Emma resist for a time, but eventually it did start affecting her as well. I think it did affect Regina, when she started to Command Emma in Camelot to get her to see the truth. I think it even affected Belle, maybe not in Storybrooke, but in the Underworld.

Bottom line, I think this theory may be on point. whether this is something that the writers have considered is another story, though.