Board Thread:What If?/@comment-5674726-20130722102922/@comment-5674726-20130801054929

Fimber wrote: Since the prophecy is older than mankind or even life itself (according to the Vilia), Arthur's birth was predetermined and Nimueh obviously knew of the prophecy/destiny which also shows that Merlin's birth was only necessary because Arthur's birth causes Igraine's death which then causes the Great Purge and so on...

Technically, the Vilia said that Merlin had great power and a future that was written before the dawn of time, and made no mention of Arthur. It's possible that Nimueh brought Arthur into the world before he was meant to be there and, if so, it could be why he and Merlin failed to achieve their alleged destiny.