This scene keeps playing out in my head of Arthur finding out and being terribly disappointed in Merlin. Not just for the usurping of power, but Arthur thought they were friends, and Merlin was going through a lot of emotional stuff that he hid from Arthur. Like, as a friend, I'm sure Arthur would have liked to know that Merlin had found and then lost his father. In the last two episodes, Arthur spends a lot of time asking what's going on with Merlin, showing genuine concern, and Merlin's just lying to him.

I mean, at this point, Merlin's secrets have so much momentum, even when Arthur becomes king, he'd have to keep hiding.

I did actually enjoy series two quite a bit, but they've made it rather hard for me to go to my happy place.