Board Thread:General Discussion/@comment-24945543-20140515174213/@comment-24938134-20140523221214

Possibly, he could have decided she was too unstable and locked her in the urn. Better safe than frozen solid.

My theory is ridiculous, but then again the entire show is so.......:

Malcolm got someone pregnant when they were teenagers - Elsa and then a few years later they had Anna. Elsa could have accidentally killed her mother so Malcolm locked her away. He remarried, Rumpel was born but his wife died or left (wouldn't you?). Anyway Elsa was too much of a threat or maybe she froze Arendelle, or was about to so the Blue Fairy locked her in the urn. Anna left to try and find her but got herself locked up as well. Rumpel nicked the urns from the Blue Fairy because of reasons, and still has Anna in his Vault, but doesn't know it's his sister.

I only theorise this because the writers want Robbie Kay back for season 4, and she'll be related to Henry. Both of which are high priority for the writers :P

That and I hate the Blue Fairy. I don't know why, but there's something about that talking jellyfish that just irks me :/