The first time they kiss is an accident.
Honestly, it wasn't meant to happen.
It was some time before everything became complicated; before Uther died, before Arthur was crowned king, before Gwen became queen. Before any of that, really, but it was still a while after Morgana left and Morgause died.
Merlin was, naturally, trying to get Arthur up on one slow, stormy morning. "Arthur, come on," Merlin insisted. "You have to get up, you know. You have duties like every other prince in the world."
"Not before sunrise," was Arthur's grunting response, turning to face the other way.
"The sun did rise," Merlin said with a roll of his eyes. "You just think it's still dark out because of the storm. But I assure you, sire," – always the one to tack on the formalities with sarcasm in instances such as this – "It is daytime. Which means it's time to get out of bed."
Arthur groaned a complaint that brinks on being a whine, rolling over as Merlin gives his body a tug. And that was when it happened: Arthur's momentum paired with Merlin's clumsiness landed Merlin atop his master, lips meshing awkwardly, but definitively.
They both froze in place – never a practical reaction – before violently jerking apart. Merlin stumbled back a few steps closer to the window, and Arthur nearly fell out of bed as he scurried to its other side.
"What on Earth –" Arthur began with a gasp, and Merlin was pink-face and shaking his head briskly.
"I-I-I don't know," he stuttered. "I'm sorry, I didn't think that would– er, that is, I didn't expect– um…"
Arthur briefly touched his lips in puzzlement before shaking it off and standing from his bed. "Never mind it. Just… don't let it happen again, understand? And get my breakfast!"
The second time they kissed wasn't necessarily an accident, but it was indeed a mistake.
Because, honestly, this one wasn't meant to happen, either.
"I didn't want you to feel that you were alone," Merlin murmured to Arthur in condolence, because he did feel this was entirely his fault, despite Morgana's aid in the tragedy.
Uther was dead, and while Merlin knew deep down inside that it was what had to – and, in a sense, needed to for destiny purposes – happen eventually, it didn't hurt any less to watch Arthur walk around with so much anguish pouring from him. It wounded Merlin to see his master in so much grief; because Uther didn't matter as much to Merlin, but Arthur's feelings matter the world to him.
"You're a loyal friend, Merlin," Arthur replied quietly, and that was it. He started to walk away.
"You don't –" Merlin called after him, trailing behind him as he usually did – "You shouldn't withhold your pain like that. Please… I'm your friend. You even said so yourself, just now. So… so share it with me," he prodded as kindly as possible, his hand on Arthur's arm, stilling the to-be-crowned king.
Arthur was shaking. Merlin could feel the tremors beneath his fingertips, vague and noticeable at the same time. Being restrained, Merlin realized. He looked up, trying to catch a glimpse at Arthur's face.
Arthur turned, slowly, and his previously deadpan expression was aflame with heartache, and it stole the breath from Merlin's lungs. His breathing hitched in his throat and his heart slowed to a painful beat.
"Arthur…" Merlin began, dropping his hand. He couldn't finish whatever sentiment he had been about to say, anything about loss and pain. The blond turned fully around and embraced his manservant, the quivers full-strength now. Merlin held on, trying to be as much an anchor as he could, given his smaller frame but equal height. "This will pass," Merlin said, trying to be helpful. "Soon, you'll be so busy you won't have time to grieve, eh?"
Arthur snorted something between a sob and a scoff, most likely because he was torn between feeling more pain at that thought and some sense of bitter humor at it instead. In the end, Arthur pulled away, chain mail rattling, and wiped his eyes and kept them trained to the windows of the corridor.
"That didn't happen," he said, voice clearer than how Merlin thought it would sound after such crying. But, then it happened. Arthur's eyes panned over to Merlin's face, flickered temporarily to Merlin's lips, and then his pupils dilated.
Merlin raised a brow, about to ask, but he was silenced by Arthur's mouth, fleeting and tender on his own. When Arthur pulled back this time, he looked both ashamed of himself and relieved, somehow.
And he walked away again.
And Merlin didn't follow him that time, because he supposed the whole thing was due to a fragile emotional state and nothing else, and that Arthur needed time to think things properly through.
But it wasn't an accident, and that helped Merlin understand the third kiss.
And the fourth.
And the fifth.
There became more and more moments when Arthur would glance down at Merlin's lips, his pupils would dilate or his gaze would soften, and the next thing Merlin knew, they would be kissing for the shortest of seconds before departing to do some thing or another that one of them had to do.
Like Merlin with a chore, or Arthur to have a conference. It would happen in the royal tent before something challenging, or it would happen around the campfire after everyone else had gone to sleep.
And then there came the protection. In which Arthur was so careful with Merlin's well-being that Merlin began to wonder if the young king had somehow become his personal bodyguard. Which was ridiculous and backwards, because Merlin is supposed to be – and more often than not is – the one protecting Arthur from some threat or another.
To Merlin, however, this only meant that those kisses were important, something preserving their odd relationship. Because even when Arthur marries Gwen, Merlin isn't jealous or angry or disappointed, because he knows that the two are right for one another, and for Camelot, and for history, and that Merlin belongs where he is: by Arthur's side, as his servant and his advisor and his friend. As his magician, as his protector, as his closest ally.
And sure, it can be difficult, because anyone could figure them out at any time; someone could be a witness to their lingering touches and shared stares and brief touches of lips. And if they did see it, Merlin has no doubt that Gwen would find out, and it might hurt her deeply, and God knows that would hurt Merlin as well, because Gwen has always been his friend and he would never purposely take her husband from her.
So it is a risk, yes. Every waking moment he and Arthur are in the same room together, it is a risk. But it's a risk Merlin is willing to take, because he can genuinely say (in his own mind only) that he loves Arthur. Loves him in the only way someone can love another person to the extent of laying down their life willingly for that person and smiling at that person's jokes and taking the ugly with the lovely and the horrid with the good and liking that person all the same.
And Merlin knows, even without Arthur saying it, that he feels the same way.
The spark in the room during that first kiss was proof of that. And everything that followed only solidified Merlin's belief in that one thought.
And that's enough.