Ok so, we all know that the reveal of Merlin's magic to Arthur has been going on for too long--so long that I'm actually beginning to think of this theory as a possibility...
For some reason or another Merlin's going to be in a position where he has a chance to tell Arthur of his secret, but this time he actually goes through with it: "Arthur..."
"Yes Merlin? What is it?"
"Well...it's difficult to say"
"Spit it out, Merlin."
Merlin swallows, then looks at his friend, "I have a...secret."
Arthur looks up.
Merlin: "I should have told you a long time ago...it's kind of hard to--"
"Just tell me, Merlin."
long awkward silence....
"I have magic," Merlin...I don't know, shows him a flame on his hand or something.
Arthur nodding, "I know."
"What?!"
"Oh Merlin, I've known you've had magic forever. Did you really think I was that stupid?"
"Why didn't you tell me?"
"Well I couldn't acknowledge it or I'd have to kill you."
"How long have you known?"
"Long enough to know it was you dressed as that old woman."
Merlin: face palm. "And you've never given me any credit for any of the times that I saved you and Camelot?"
"Well, why would I when I get all of the glory?" Arthur smiles, "You are such a coward Merlin, I can't believe this has taken you ten years to tell me," shaking his head.
I know, I've always thought of this as a stupid theory, but I'm now having second thoughts. Please comment! :)