To put it simply, Telanyas Atla, the son of Michael, the supreme commander of the Celestial Legion, went to the human world to provoke Merlin. He threw him on a little kid who was suspected of being abused. He worked as a domestic servant for 11 years. In the end, he was told that you were the savior of the magic world and was given the responsibility to defeat the Dark Lord. Go, the magic world will be finished without you.
Then, Trayas realized that he had been fooled for 11 years.