Merlin grew up in the small village of Ealdor with his mother, Hunith. They sometimes visited the city of Camelot for goods if needed, but mostly stayed on the farm. As he had been born with magic, Merlin became cautious of using magic in front of others even though they were not in Camelot's kingdom.
When he was older and his best friend Will learned of his magic, Merlin's mother insisted that it was not safe for him anymore even though he knew that William would keep his secret. Regardless, he packed up, said his goodbyes and left. Hunith left him a note for his Uncle Gaius, her older brother, in Camelot and he was to stay and learn under his tutelage.
He did not like finding out how dangerous Camelot was for someone like him, but he stayed. His uncle helped him a great deal and he worked for him until he came across Prince Arthur, who was quite the prat. It ended up turning out that he saved his life without even thinking about it at the time and King Uther gave him the position of Arthur's manservant.
Merlin was not happy at first about being Arthur's manservant, but eventually he got used to working for him and saved his life many times. Though that mostly was because the dragon he met told him that he was destined to help Arthur rule a better Albion than it was now.
When Merlin found out that his father was alive, he was thrilled, though the man died almost as soon as he found him. Balinor told him that he was a Dragonlord and thus, would have the power to calm Kilgarrah, who had been attacking Camelot.
Things took a turn after Arthur became King and Uther died. Morgana, the King's Ward and Arthur's sister, had turned against them all. Merlin blamed himself because he'd hurt her when he could have helped her and so they were forced into a war.
Morgana had found out a way to get rid him of his magic and he had to go get it back. he was too late to the fields of Camlann. Arthur had been mortally wounded and he took him to Avalon, but even that was too late and he had to lay Arthur to rest in the waters of Avalon. Merlin was told that Arthur would return one day, so he waited. For over a thousand years he waited for Arthur's return, hoping that he would be back one day and they could unite Albion like he'd been told so long ago that he would do.
These days Merlin is the High warlock of London, assisting those who need his help and doing his best to keep his nose out of things he shouldn't get involved in. He also is the originator of the Order of Merlin & is well known within the Wizarding World too.