What is and What Should Never Be

What if one wish you had, one you hadn't even said aloud, was granted? What if it changed everything? - when Arthur and Merlin go on a hunt for a magical creature - a 'Djinn' - which supposedly has the power to grant wishes, Athur is attacked. He then wakes up in Camelot, alive and well. But something is different... what has changed? And is he willing to live with the cost?