Who Is Nimue on Once Upon a Time?

In the last episode of Once Upon a Time, the quest to find Merlin is finally fulfilled, only to send the citizens of Storybrooke on another wild goose chase. At the very end, Merlin warns the gang via hologram, or voicemail as Regina puts it, that he's been discovered, and their only hope of removing the darkness from Emma is to find a person named Nimue. So, the question remains, who exactly is this mysterious character? The new photos for next week's episode give us a few ideas, but there is a lot more about Nimue in Arthurian legend. Keep reading for a few theories we have about her character on the show.

She Is Merlin's True Love
ABC

She Is Merlin's True Love

According to Arthurian legend, Nimue is referred to "the Lady of the Lake" and was Merlin's great love. He allegedly fell head over heels and taught her all of his magic secrets.

Then She Betrays Him
ABC

Then She Betrays Him

After learning all there is to know about magic, the story goes that the Lady of the Lake used her power to trap Merlin in a tree. While we wouldn't put it past the writers to throw in another complicated relationship on the show, this theory does seem a little odd since we already know that it's the Dark One who traps Merlin in the tree to begin with.

Does She Become the Dark One?
ABC

Does She Become the Dark One?

Merlin sheds a tear for his lost love, but maybe he is actually shedding a tear for the darkness that consumed her. Is it possible that Nimue is actually the original Dark One? The show has been known to throw some major curve balls before, so this theory could totally be true. Guess we will just have to wait until Sunday night to find out for sure!