The one piece of relationship advice Hunith ever gave her son was, "I have a few things I keep from you, just as there are a few things you'll keep from me. In every relationship there are a few secrets. Even among lovers. No matter how loving and no matter how close, everyone hides something from their partner."
At the time Merlin had been ten, and wanting to know about his father, so he'd been a little too busy being angry to really think about his mother's words. But when he met Freya, he remembered.
Part of it was bad timing, he supposed. He and Arthur weren't in the best place at the moment. In Arthur's defense, it wasn't entirely his fault. After Merlin had been forced to lie about Morgause to stop Arthur from killing his own father, Merlin had felt… actually, he didn't have words for how he felt. He was sick of hiding his true abilities from Arthur. He was tired of lying and sneaking around behind Arthur's back. He doubted, now, if Arthur even truly cared for him. How could he, when he didn't know who Merlin truly was?
These thoughts plagued him night and day, turning dreams into nightmares and distracting him at his work. He drew into himself, which in turn drew him away from Arthur, which in turn made Arthur irritated. The prince knew something was wrong with Merlin, but he didn't know what it was and Merlin wouldn't tell him, and it frustrated him.
They had a lot of petty arguments.
And then—then Merlin met Freya.
This, he thought, was what love was supposed to be like. Sweet and gentle, so natural that it was like breathing, and distracting in a joyful, dizzying sort of way. No pain or anger, just happiness. He'd never had a "first love" so to speak. The only friend he had in Ealdor was Will and he wouldn't kiss Will if you offered him all the wealth in Camelot. Arthur was—Arthur was a lot of things, good and bad, and half the time he made Merlin so confused inside that he didn't even know which way was up.
Freya was kind, and sweet, and Merlin could make her laugh. What was more, he could be himself around her. He didn't have to lie or hide, or feel ashamed.
He wanted to run away with her. He truly did. Camelot suddenly felt oppressing. Even Arthur felt oppressing. He just wanted to leave it all, to find a place with just the two of them. He wanted to escape his destiny.
But then Freya died, and he realized what a fool he was.
Love like that, it didn't last. It died out or grew until it was as complicated and painful as what he felt for Arthur. And as he watched the burning boat make its way to the center of the lake he knew, he couldn't run. He couldn't hide. Not from destiny and not from himself.
It startled him how easily he was able to let go of Freya. He ached for her, for what she had gone through and the fate she did not deserve, and he railed against the deities for letting such a sweet creature die. But with every step he took toward Camelot, the more Freya's face seemed to fade away, replaced by another, more familiar one.
And when Arthur apologized, taking his face in his hands and kissing him, Merlin knew that nothing, nothing in the world felt as good as this. And maybe it was painful and maybe half the time he was confused and angry and lost but if that was the price he had to pay for having this, then he'd pay it every time.
Arthur might have been a prat, but he was Merlin's prat, and Merlin silently thanked Freya for reminding him of that.