Board Thread:Character Discussion/@comment-25355646-20150302022703/@comment-26237024-20150715201533

The "Dark Curse", like other uses of magic, can be used for good or evil. It's neutral. Regina (and Rumpel) used it for nefarious means. Pan almost used it for nefarious means. Snow, David and Regina used it for good - to get close to Emma, so that the latter can defeat Zelena.

Apparently, anyone - whether he or she is the curse's caster or not - can alter the curse with slightly different details. Rumpel made sure that the first curse would be broken by Emma. Regina added a trigger to it and ensured that everyone would have no memories of their Enchanted Forest identities. I don't know what details Pan had in mind. Zelena put in her two cents to the curse that Snow had cast by ensuring that everyone, aside from herself (and possibly Rumpel) would have no memories of that last year in the Enchanted Forest, which included her.

Like magic itself, the curse is neutral.