The prophecy says: "The bane of Arthur is the druid boy — he will tear down the walls of Camelot." Everyone (including the audience) assumes "bane" means enemy/destroyer. But by the episode's end:
Gwen hesitates, looking back at the road to Camelot, then at her loyal friend. She takes his hand.
Love is not enough to save a kingdom, Merlin. But perhaps... perhaps distance will give him the clarity he needs.
(A small, sad smile) He always did have a terrible aim when he was angry.
Merlin? What are you doing here? Arthur exiled me.
(Turning to the window, his voice low) It has shaken my faith in myself.