Merlin is never scared of Arthur's bad moods. He's annoyed by them sometimes, but it really doesn't matter how Arthur lashes out, Merlin is way beyond ever being intimidated by it. And it's so clear that Arthur wants him there. Not for the first time, Arthur goes to sacrifice himself and needs the comfort of Merlin with him.

This is a really good point.

I didn't particularly like the way they poked at each other this episode, but it makes sense the way you put it in context.

Can't wait to see how the rest of the season plays out.