♒ - a secret that’s obvious
( Arthur is particular about who he trusts. But when he trusts someone, he trusts them fully and unconditionally. But once his trust is betrayed, it’s difficult for him to accept that the person is not as he saw them before.
Morgana, he had no trouble trusting. She was as good as family to him, though he did have a bit of a crush on her for a while. But he had no doubts about her until she betrayed him and his father. He kept making excuses for her in his head, at first. But then he realized that there was no turning back for her. She was a lost cause.
Guinevere, he grew to trust unknowingly. She was always loyal to Morgana, and therefore the royal family. She told him exactly what he was like to the people around him, and he used her words to shape himself. He couldn’t believe that she would betray him, even for love. It hurt so badly for him to see her that he banished her from Camelot. He knew maybe one day he would forgive her. But until then, she was better off far away from him.
Merlin—-Merlin was different. He was an incompetent servant who had a bit of luck that earned him a place in the royal household. But there was something about him. He wasn’t an ordinary servant, and whatever it was that made him special made Arthur trust him. He didn’t know it was destiny. He only knew that his servant was his best friend, his confidant. Hearing that his friend had lied to him for years hurt him worse than anyone else ever had. But he was able to forgive him the quickest because he saw that everything Merlin had done was selfless.
Arthur cares little for himself, and he trusts those that care about the well-being of others. If you care for the greater good, he will trust you too. )