Board Thread:Spoilers!/@comment-6175354-20130221220310/@comment-6175354-20130305151903

121.219.67.18 wrote: Perhaps the "magic is about emotion" quote might reference why cora and regina turned evil; it's not the magic that corrupts, but their feelings that corrupt their magic. IE: Both had broken hearts and sought a way to escape from their broken hearts thus they desired power and thus used magic for their purposes. While you are probably correct about Regina's broken heart, corrupting her magic. I cannot help but feel Cora's turn to evil, was triggered by her hate for Eva.

From the promo/bts pictures, it looks like Cora was a desperate social climber. Once she got her first taste of magic, she became obsessed with gaining more power. Then add the fact, that the price for Rumplestiltskin's help, was probably her own child.