Morgana and Merlin in “The Mark of Nimueh”

Merlin, I wanted you to know your secret's safe with me.

My secret?

Come on. Don't pretend. I know what you did.

You do?

I saw it with my own eyes.

You did?

I understand why you don't want anyone to know.

Well, obviously...

I won't tell anyone. You don't mind me talking to you about it?

No. It's... you have no idea how hard it is to keep this hidden.

Well, you can continue to deny it but... I think Gwen's a very lucky woman.