I just learned Elizabeth Mitchell joined the cast. She is an unknown villain. So, an idea crossed my mind...
Do you remember the TRUE Snow Queen's tale? The one with a girl who went to save her friend wich heart was frozen.
So, the girl saved the boy, unfrozed his heart, and the kids went home. That's the end of the Anderson's story.
Now, the theory starts. The Snow Queen was angry, because she lost (hahaha... lost... hihi... get it? "Lost" Elizabeth Mitchell played in. ^^)
She didn't want to let the kids win definitely. So, years passed, the kids (who grown up) got married and became King and Queen of Arandelle.
The Queen was waiting for the first baby, and at this moment, Snow Queen appeared and cursed the baby before he was born. The baby got powerful winter powers and very hard to control. You get it, the baby is actually Elsa.
Well, you know the rest of the story.
Hope you enjoyed it and tell me what do you think.