[When Charlie's expression changes, Merlin's already reaching out for her out of complete impulse and when he notices, he doesn't stop himself even if he very briefly considers it. He really doesn't see why she would mind it, really - that's just a rather stupid thought because she's never denied his comfort before - and so he places his hand on her shoulder, rubbing it gently.

So her father had tried to protect her... and died. And Merlin's throat goes tight because his father died protecting him, and she got to see him die at such a young age, and... God.]

I'm sorry.

[It feels like such a ridiculous thing to say, really, but to him, at least... it's come to mean a great deal.]