I want to see more of Merlin been a feral magic been. I know that many want to think that Arthur would accept Merlin magic with open arms, but I like the drama and possibilities that come with the idea of that not been the case.
Picture with me, Arthur, in the rage of the moment and feeling betray exiles Merlin, who after accomplish the prophecy and avoiding Arthur to die, realizes that there is nothing more for him in Camelot, there is nothing more for him in general, he has done his duty and now he has no other purpose to follow.
His mother? She is a strong woman, he can protect her with his powers for the distance, that would save her some hard moments of having to lie for Merlin sake; His friends? They are knights of Camelot and loyal to Arthur, he would not want to made them choose; Gaius? The man deserves an apprentice that can give their all to the medicine, and he has done so much for Camelot that Merlin can't bring him down with him. It is way easier if Merlin just leaves quietly, so he does.
He goes to the woods and for the first time in his life he lets the magic guide him without limitations, and he can feel every tree and flower, every animal and river and he just let his mind get lost in it. He lives as a hermit at first, but his magic is slowly taking over his human side, because he has no connection to the humans, he becomes the pure magic he always was. He has no rules to follows, no alliancies, he can just be magic, free and without thought behind the mere fact of existing.
He is not Merlin anymore, Merlin was a servant, sneaky and sassy, with duties with the men, and a kingdom to serve. He becomes Emrys, powerful, a magic authority, the encarnation of magic, a force of nature, a power that cannot be deny, like the sun rising in the east, and the waves breaking in the shore.
If we want to add to the drama, and of course I would want to add to the drama, at some point Arthur, who after a long while (this can't happen in some weeks guys, we are talking months at least) more cold minded and having make his own deep reflections, decides to look for Merlin.
Maybe he wants to remove his exile, maybe he misses his loyal servant, maybe he just wants to have a chat with Merlin, hear his side of the story, let him explain, as he did not let him do back when he exiled him, so he is determine to find him and have some answers.
I think it would be interesting if Kilgharrah, the druids or even Freya tell him of Merlin condition, of how he has lost himself, but Arthur doesn't believe this, because in his mind Merlin is Merlin.
But then he finds Merlin, or he finds Emrys, and he realize that he is in front of a deity, deity of magic, and he is only human.
Merlin/Emrys does not call Arthur by his name at all, he just refers to him as "Once and Future King".
Arthur tries to tease Merlin/Emrys in a effort to make him react, but he is not responsive.
Making Merlin/Emrys to speak is quite the deed.
If the knights are there, they have to be tension between them and Arthur, because some agree with Merlin exile other don't and that makes everything difficult.
Finding Merlin/Emrys feels like a paranormal hunt, or he falls in the uncanny side making Arthur and the others feel uneasy around him.