User blog comment:Ḡwẵine Ḹٍٍkƨ Ĺiĸe Ͼềлȑềd/Arthur's Reaction After Learning Merlin's Magic/@comment-4495575-20120428122131

Good question! It really depends on the situation. But I guess in the end Arthur will be angry and upset as he was betrayed and lied to by his closest friend as he won't see things from Merlin's point of view :(

Let's hope the reveal is happy!