User blog comment:Shutupmerlin8/THANK GOD!!!!!/@comment-4892425-20121215231453/@comment-5253758-20121216220548

@Knightofthecart Mordred did not intend to betray Arthur. His plan was not to leave with Kara and join Morgana, but to be left alone to leave with her. They could go away and live peacefully together. He was planning to convince her to change her mind about Arthur. He even said that in the episode.

And I still believe in what I wrote in my earlier post. Merlin has betrayed Mordred numerous times! Morganaforever gave a  lot of examples.