Board Thread:General Discussion/@comment-5817180-20150802105636/@comment-8345449-20151201103335

According to Belle, TLK will only work if the afflicted doesn't want the curse (else it isn't a curse anymore). Rumple wanted power that came with being a DO so it didn't work for him.

Emma wasn't ready to let go of the darkness when Hook kissed her, so it didn't work for her. And when both Hook and Emma were ready to let go of the darkness (shortly after Hook was turned), the darkness had already multiplied so TLK was n enough.

The only time when TLK possibly could have worked was right after when Emma just lit the Promethean flame (after the "I want a future with you" heart-to-heart). But they didn't kiss so...