Scared For You

Merlin felt the golden light fade from his eyes as he looked to Arthur, who was standing mere meters away from him. He didn't even have to look at the King to feel the expression on his face.

No sooner had he looked to the other man; Merlin had frozen on the spot. It was as if the world had stopped at their feet and that he and Arthur were the only two people standing in it.

OR

Merlin reveals his magic to save Arthur's life in the midst of a battle. Wracked with fear for Arthur, he runs away, and Arthur finds himself unable to let Merlin go.