AN: My own little version of what happened after the series finale. Written for all those who cried with me at the end, and couldn't help but pray for a reunion of our favorite king and warlock pair :)
There were days Merlin wondered if Kilgarrah's last words to him had been some type of cruel joke.
It had been over one-thousand years since Arthur had died, one-thousand lonely years as Merlin waited for the other half of himself to be returned to him, but there had been no hint of the former king. Still, holding onto the hope that he might returned seemed better than resigning himself to the fact that he would be alone forever.
There had been so many times when Merlin had been certain Arthur would return, that Albion obviously had great need of a leader like him to rise up and lead them out of darkness, but Arthur hadn't come. His king remained at the bottom of a lake through wars and disasters, famines and plagues, never once returning to lead his land out of darkness. Merlin tried to cling to the fact that Arthur was the Once and Future King, but with every moment that he passed alone, the future seemed further and further away.
Even though it was so long ago, Merlin still remembered his time in Camelot like it was yesterday. The years he had spent as Arthur's servant had been the best of his life. He had a purpose, his life had meaning. Once Arthur died, he lost all of that.
It took him three days after Arthur had died for him to work up the courage to return to Camelot, and when he did finally get to the city he couldn't bear to remain there for long. The city lacking its king was a constant to reminder to Merlin of his failure. When Gwen had seen him entering alone, she had burst into tears. He held her, trying his best to give some comfort, but had been quite glad when Leon had come to relieve him of the mourning queen. Percival had told him of Gwaine's death and Gaius had watched him with worried eyes as he wandered aimlessly through the castle he had once thought of as home.
But Camelot had only been his home while Arthur was there. The castle felt so much colder without Arthur's teasing, without his smile, without his guidance. So Merlin ran. He hadn't even stayed long enough to see Gwen's coronation. Part of him felt guilty for leaving them now, but he also knew his duty was done. He was made to serve Arthur, and Arthur was gone.
Merlin hadn't really known where he was running until he arrived back at his mother's doorstep, tear tracks staining his face. Hunith had tried her best to help him, to let him go back to the way things were before he had set out towards Camelot, before the fateful day when he met Arthur and everything changed. He was grateful to her for that, if it hadn't been for her support he was certain he would have lost himself completely. But, after about three months of trying to forget what had happened over the past ten years, Merlin realized that it was impossible. He gave his mother one last hug before he set back out towards the lake of Avalon, swearing that if he could do nothing else, he would protect Arthur's final resting place until the king returned.
Kilgarrah had died only a few months after Merlin's return to the Lake of Avalon, his rotting body discovered by a patrol sent towards the Lands of Nemeth after there had been rumors of the ground quaking and fear of some new evil spread through the kingdom. Merlin had visited his body briefly, raising a great mountain of boulders around the dead beast that had been the first to instruct him of his destiny. Merlin hadn't cried at all. All his tears had been spent mourning Arthur.
As the Lake of Avalon was only a day's ride from Camelot, Merlin could still watch from a distance as Queen Guinevere brought the country to even greater heights. The widowed queen and her loyal knights continued on Arthur's quest to unite the kingdoms, leading Albion into a new era of peace and prosperity. Merlin had returned for a short period after Gaius' death, serving as the court physician until a more suitable replacement could be found, but besides that brief period he tried to avoid the city as much as possible. The last time he set foot in the castle was on the day Guinevere died, leaving her kingdom to Percival's oldest son. It had been so strange to see her withered face and graying hair with his eternally youthful eyes. She had died peacefully, smiling as she was reunited with Arthur at last, a privilege Merlin would never be granted.
Once again Merlin did not wait around for the coronation, but vanished from the city leaving only the tales that had been passed on by Gwen, Percival, and Leon to the next generation. He had no reason to return to the kingdom that could only provide a terrible reminder to him of all he had lost, so he settled permanently by the Lake of Avalon, watching over the passage way to the next land as he was unable to go himself.
As time went on it became more and more difficult for Merlin to stay on the outskirts of society. The cities of men grew, moving ever-closer to the Lake of Avalon and Merlin's small hut that sat on its bank. He watched them from a distance, afraid of what would happen if his abnormality was ever discovered, but also determined to remain the guardian of the lake that held the bodies of his king, love, and trusted friend. Ever since he had stepped into the center of the crystal cave he had known that the Druid's name for him was less of a title and more of a description. He was Emrys, everlasting, eternal. No matter what happened, he continued on. The magic of the earth sustained him, keeping him as its protector since his original purpose was served. So, when houses and buildings finally did spring up around the lake Merlin had been living near for centuries, Merlin had to come up with a plan to remain at his post without being discovered for what he really was.
He used aging potions and other spells to periodically change his appearance, hoping that the people of the small town that had formed around him would never notice just how different he was. He watched over them, serving as a doctor to those who needed it, but mainly kept to himself, trying his best to avoid people at all costs.
The world changed before his weary eyes, as magic practically vanished from every corner, replaced with something called science. Merlin supposed this would make Gaius smile, but some of the things science was used for were terrifying. Even in his secluded corner of the world Merlin heard of the horrors of the atom bomb, saw the effects of biological warfare, and prayed that Arthur would come back to free the world from these terrible inventions. But not all technology was bad. Merlin couldn't help but smile when he thought of how incredibly useful things like computers, especially with the new tool of the internet, would have been when he had to spend all night searching through Gaius' old books for some strange beast or potion. And now getting to faraway places was simple, no more horses, and therefore no more stables to muck out. He had never been on one, but the airplanes that periodically soared over the lake fascinated him. This new age had dragons of its own.
But, even with all these changes, Merlin couldn't help but long for the past. He felt his heart beat quicken each time he saw a familiar shade of blond hair or blue eyes as he strolled through the small town, but each time he was let down. And with every passing day it seemed less and less likely that Arthur would return.
Merlin rarely cried anymore, but on this night he felt cold tears slip down his cheeks once more, currently the wrinkled cheek of an old man as he hid his condition from the people living around him. The sky seemed to mourn with him as rain pelted against his windows. He was thinking of attempting to sleep when he heard a knock on the door.
He rarely got visitors, although from time to time some group would come trying to get him to give them money or join some religion. Assuming it was simply another one of them, Merlin ignored the knock, hoping the pouring rain would send them away. Unfortunately, it didn't seem this caller would simply leave, as the knocking continued. Merlin finally gave in, quickly drying his eyes before he hobbled over to the door and clicked open the lock. The soaked man who stood in front of him was so familiar it hurt. Merlin could only stare with wide eyes as this Arthur-duplicate said something about his car breaking down and a phone. It wasn't until the startlingly blue eyes met his that Merlin was pulled out of his trance, and he heard the words, "Do I know you?"
Merlin smiled for the first time in ages as he replied, "Yes, Arthur. I believe you do."