Board Thread:Spoilers!/@comment-5094906-20150503164016/@comment-26307323-20150503180339

Plus, remember that Maleficent was born with the balance of good and evil. Even though she embraced the evil side more she still has goodness in her, and is motivated by the love for her child. Lily never had that, but rather faced the abandonment of her mother (she thought), being left by her only true friend, and living a life that always seemed to take the wrong turn. She's got a lot of built up anger and is ready for revenge. And, Maleficent stated he wasn't interested in Snow and Charming's death but rather their long, enduring suffering; seeing Emma turn to the dark side would certainly suffice to meet that criteria.