User blog comment:Knightofthecart/Morgana has turned her back/@comment-4879894-20120313171804/@comment-4135736-20120314092451

If their mentors were the other way round, then Morgana would still have been good while Merlin would have turned evil in her place. In the very first episode, Merlin was close to becoming like Morgana is now, especially when he said that he was willing to help other people who wanted to kill Arthur so he was lucky to have a good mentor like Gaius.