I am not sure Morgause has been fully explained yet. When she first appeared, she burst her way into Camelot, killing 3 guards on the way, challenged Arthur to a fight, had him at her sword's point and challenged him to do whatever she asked 3 days hence, then when that time arrived, threatened to cut off his head and all so she could grant him his dearest wish!?!? Then she allows him to meet his dead mother who tells him his father is a shit, and she (Morgause) commiserates with him on having a shit for a father.
I mean, what the f*? Did she expect Arthur to go home, kill his father and embrace magic? Is she so cross now because he didn't? I am assuming that is the case, but it could do with a bit more explanation, seeing as this is a children's show, not Checkov. (Cant think how to spell that name).
Oh and I read something the other day that implied that Arthur would never find out about Merlin's magic. My heart sank. He has to! Of course, they need to maintain the dynamic between Arthur and Merlin, ie Arthur has to keep bullying Merlin because that is funny and what makes it worth watching, but surely they can do that and also reveal Merlins' secret? Come on script writers! I think the writing has really gone off this series and someone seriously needs to do something about it.