"There can be no place for magic in Camelot."
The writers are so cruel for this. Like Merlin is so concerned with destiny, with fate, with how he thinks the future will inevitably turn out, that he doesn't even realize his attempts to stop it are leading them in that direction. Arthur is closer than he's ever been to accepting magic; he literally asks, "what if my father was wrong?" All Merlin had to do was say Uther was wrong, that magic can't be all bad, and everything would have been fine. Everything Merlin had ever hoped, for magic to be free, for him to not have to hide who he is, for him and Arthur to fulfill their destinies, all of that would have come to pass. But Merlin, so caught up in a future he sees as closer than ever before, so wrapped up in his desperate need to prevent it, is unable to give that simple answer. Of course Arthur should accept magic; it's what Merlin has known all along. But he's become so concerned with the what-ifs, with figuring out and stopping potential threats to Arthur before they happen that he buries his feelings, what he knows to be right even though it kills him to do so, and he lies thinking it will save Arthur. Except it doesn't.
post magic reveal merlin who is so used to working in the shadows and continuing on as if he wasn’t dying the night before disappearing for a day and showing up like nothing happened until someone points out blood seeping through his clothes and merlin going “oh! whoops! lol” and arthur has a heart attack
Arthur vs Merlin on asking for the parent's blessing:
Arthur: I somehow managed to make the trip out to Ealdor without Merlin following me and asked Hunith for her blessing. I barely made it halfway through my planned speech before she was hugging me and calling me her new son. As lovely as that was I hope Guias has a more moderate reaction when I ask him next. I know he's not actually Merlin's father but he's the closest Merlin's ever had so it'd feel wrong not to ask him too for permission to marry Merlin.
Merlin: I don't know who I'd even ask for Arthur's hand. Both his parents are dead, so is his uncle the traitorous bastard, and his sister is trying to kill him. I really couldn't care less if Uther approved of me marrying Arthur anyway. If anything I hope he's glaring at us from hell as he watches his son and heir marry a sorcerer.... Maybe I'll ask Leon.
It’s a good thing that Merlin doesn’t ever push Arthur when he’s showing affection because Arthur would implode immediately if he had to think too long about it. Could you imagine the (deleted!!) sigil scene if:
Arthur: Just… take it.
Merlin: Why are you giving me this?
Arthur: *sweating*
Arthur: It’s… a bird. And you’re a bird.
Merlin: …what?
obsessed with the merlin and arthur dynamic that is characterised like:
merlin: i want him, i love him, but i can't. there are things i shouldn't tell him, not yet. but i want to. but i can't. and fate? what about fate? what about destiny? what would happen? no, i can't. there are so many things, so much-
arthur: (dramatic sigh) i wish i could love my manservant (you can), but he's my manservant (no one cares, everyone already assumes)
so when kilgharrah says “no man no matter how great can know his destiny” and then tells merlin his destiny is that bc merlin doesn’t classify as a human to him lol
merlin notices knights trailing after him while he dashes around the castle and then they follow him into town and they follow him out into the woods and arthur is being super weird about it and none of the knights at the round table are saying anything so oh fuck arthur definitely knows about merlin’s magic and is having him closely monitored bc he thinks merlin is dangerous omg its so obvious. whole time arthur is just in his chambers giggling, twirling his hair, and blushing as he writes in his diary journal that he found old rules that were used to keep his mother safe and he implemented them for his queen his beloved merlin to keep him safe
in my head after the events of camlann merlin returns to camelot and, still riddled with terrible guilt and grief, confesses to leon about everything that had happened and everything he had done, magic and all. and instead of outrage or betrayal or scorn or judgement (or even death, as he had briefly considered) leon shatters him with a deeply apologetic expression and a whispered “my friend… you must have been so afraid, and so tired.” and merlin collapses into heaving sobs against him and doesn’t get back up for a long time.