Deep in the Enchanted forest are 3 people who were originally never meant to meet and interact until fate (the author) forced them together into an adventure for them to sort out. Who are the three people? Arthur Pendragon, Snow White, and Robin Hood.
Thousands of years have passed. Albion, and all its many legends, has faded into dark memories of the Ancient World. The Enchanted Forest grows around this. Legends tell the story of a Once and Future King, the one whose worthy birth magic will pass to the Savior. All at once darkness comes for Emma Swan to fight. Merlin escapes his ancient Crystal Prison, and Arthur rises again.
After mysteriously finding a new chapter in Henry's storybook, Emma meets a mysterious old man who isn't what he seems. Once figuring out who put the new chapter in the book, Emma and the visitor must put an end to the chaos as the witch plans to overthrow Regina, all the while helping him find someone named Arthur. (DISCLAIMER: I DO NOT OWN OUAT OR MERLIN OR ANY CHARACTERS)
One day, dozens of people from many different lands (such as Camelot) are ripped from their home worlds and taken to a small town called Storybrooke. At first, they have no memory of who they are, but they remember when a young boy unlocks a hidden book. His name is Merlin.
One night, in Camelot, Prince Arthur his kidnapped. His sorcerer friend Merlin tries to stop his kidnapper, and they both end up in Storybrooke. (Near the end of Season 1)