Board Thread:Spoilers!/@comment-188360-20140512144616/@comment-6175354-20140513142832

DarlingDavies wrote: Maybe...but Rumple put her in the vault for a reason. So he fears it for some reason. Regina may not even care that she's in town. She may be too focused on her broken heart.

If Elsa's coming to town misunderstood, she may feel overwhelmed or persecuted and be unable to control her magic, like in the movie. That's pretty terrifying. OUaT might even go dark, and have Elsa accidentally kill her sister, in the flashback. Magic is fueled by emotion. Elsa being emotionally unstable, would explain why Rumplestiltskin locked her in his vault.