Arthur had been gone for so long and Merlin still waited. His hair grew and filled with white and gray strands. His smooth face gained lines from smile and frowns alike. His already marked body continued to gain new additions with each war and conflict as well as his own two left feet.
Merlin could always make himself young and blemishless again, but he won't. There were many over the years who he had told his story. Almost all of them believed it to be ramblings of a senile old man who had forgotten the truth or was just a tale tale for the kids, but a few would ask him why he would live as an old man if he could stay young forever.
He would smile sadly and say "There is an old saying 'Wrinkles mean you laughed, grey hair means you cared, and scars mean you lived.' To remove them would be to erase who I am, and he asked me to always be me."
When asked who had asked him, he would always reply, "My brother." Or at least he had until the day a little boy with golden hair and blue eyes laughed and said, "Merlin, I meant never change how you treat those around you and things like that. I never meant for you to live over a thousand years as an old man!"
After that day, the wrinkles were gone, his hair was black again for the first time in over a millennium, and his skin was once again flawless. But then again, what need did a child have of those things when his best friend and brother had returned? They would grow old together this time.
Merlin was freer that he had ever been, but his eyes still held their real age. Like he had said, "To remove them would be to erase who I am." Arthur understood and accepted that.
The time of waiting was over, but that didn't mean the the past no longer needed to be remembered, it just meant that he no longer had to do it alone.