I've been listening to a lot of Safetysuit lately. I can only apologise.
All credit to the Merlin writers and the legend.
All credit for Someone Like You to Safetysuit.

Arthur had never really considered Merlin.
Sometimes it startled him how much he really didn't actually know about the young boy.
Of course, he knew the basics; skinny, dark haired, pale, clumsy, effortlessly lazy, etc etc all present and correct, but he didn't know too much about Merlin that maybe friends were supposed to know.
He knew where he had lived previously, had visited it even, had helped him fight for it.
He'd met his Mother and a friend, but really, he found he didn't know him that well at all.

In the beginning, Merlin was just another manservant, someone he could order around and someone to give jobs to that he didn't want to do, but things had changed, and no matter what his Father or anyone said, it was for the better.
Merlin was his friend, and as much as it frightened Arthur a little, he was his friend first and foremost. Not Prince and Servant, Future King and lowly slave, friends.
Equals.
At least, that was how Arthur saw it.

He was glad of it actually, no matter how much Merlin annoyed and frustrated him sometimes.
He was glad that he had someone beside him who believed in him, who had faith that one day Arthur would be the best King that Camelot would ever have. Someone who believed this with every pore of their being was highly reassuring to Arthur, because sometimes he didn't think he could be that person.
Yes, he was glad to have someone like Merlin.
No, not just someone like him, actually him.
He was glad to have Merlin.

In that instant, Arthur knew exactly who Merlin was.
Merlin was the strongest person Arthur knew. He was brave and loyal and trustworthy. He was selfless and faithful, quietly intelligent and stubbornly determined. He was wonderful.
He was a constant enigma, and he kept him on his toes and gave him the strength to believe that when he made tough decisions, they were the right decisions to make.
Yes, he was lazy and often late, walked like he had two left feet and was sometimes utterly incompetent, but he was his friend, his best friend, and Arthur felt like he could let everything else slide if only Merlin stayed that way.
Sometimes you can be looking at someone, but not really seeing them, and it just takes time to realise that they have been, and always will be there for you, takes time to realise that they truly are everything to you. Arthur felt like he'd just come out of the dark and was seeing light for the first time.

"Everything alright, Sire?," the dark haired boy asked from his chamber doorway.
Arthur looked over at him, blinked.
"Fine, fine."
"Good. Want me to muck out the stables then, I suppose?," he asked with a sigh.
It was at this point that Arthur realised he was so very, very, very grateful to have someone like – no – Merlin in his life.
"No, you know what Merlin? Let's go for a ride into the Woods, it hasn't been this light for a very long time," he said, smiling.
"Um, okay, I'll go and fetch the horses," the boy gave him a queer look as if he'd contracted some sort of fever, but made to leave anyway, looking if not a little brighter now that he knew he wouldn't be scraping the muck out of the stables at least.
"Oh and Merlin," Arthur called as the boy pulled the door half shut behind him.
Dark hair and a pale face peered back round the doorway, features pulled into a quizzical gesture.
"Yes, Sire?."
"It's Arthur, from now on, to you."
Merlin paused for a moment, and then beamed brightly.
"Thank you, Arthur."
Arthur smiled back.
Maybe, just maybe, he was the source of Merlin's strength, too.

If I could be with someone like you,
Would you, would you be strong enough for me,
And if I could stay with someone like you,
Would you, would you be strong enough for me?.

Someone Like You - Safetysuit.