Disclaimer: Characters and situations owned by the BBC.
Spoiler: For both seasons.
What does it feel like, Will once asked, half awed and half scared, what does it feel like, doing magic? Merlin hadn't been able to reply with anything more helpful than "like nothing else in the world". Because it does.
Not always, of course. Minor spells are just something like breathing. Keep a broom from falling, push that sword just a bit to the side; take a breath in, take a breath out, it's really not that different. You don't think about it, you just do it. But transforming something: cold steel to heat, stone to flesh and fur and bark of a living dog, air to fire; life to death. That feels unique. He calls the magic to him and it comes, it rolls through him, fills him completely, and when it leaves him again, the world is a bit different, every time.
After the end of the plague and her release, Gwen had invited him to share a meal with herself and her father, and Merlin spent a good hour afterwards watching Tom the blacksmith at his craft. Watched the passion, the care and the satisfaction afterwards. Gwen said her father could recognize every sword he ever made. "And every pot, too," Tom added, laughing. So maybe that was similar, but Tom the blacksmith is dead now, and Merlin can never ask.
One of Gaius' books says you should organize your memories like a house, store them in different chambers, depending on what kind of memories they are. Merlin considers this useful advice, and not just because he has a lot to remember. Spells for healing go with Gaius' study, cluttered but homely, full of bright colours, smelling like spices and mint. So do the every day lies. He imagines them like the leeches Gaius uses, a necessary evil, but sometimes you have to clean up the place they're kept in and then suddenly they make you want to retch.
Spells that are in any way connected to fire, except one, he puts in his mind's version of Camelot's kitchens, which are almost like the real thing, except for having an additional hearth that really belongs in the home of Merlin's mother. Heat, light, warmth, all of this comes to him in the morning when he goes there to pick up Arthur's breakfast and chat with Gwen who has just arrived from the lower town to prepare Morgana's. It's still dark, the sky pale with first light, and cold in the stone stairways, even in summer, so the warmth the kitchen exudes when Merlin goes there is something he basks in. It's the memory he uses when lighting a nightly fire when they're camping in the woods. Or to boil water, and if he goes over the top with this sometimes, certain princes have only themselves to blame. The memory of how to conjure up lightning, though, that's something Merlin keeps far away from the kitchen. Instead, he keeps it deep, deep, down underneath the castle, in the caves where the dragon lives.
We're not friends, the dragon told him once, we're more. We're kin, you and I. It wasn't until Merlin called lightning from the sky to destroy Nimueh and restore Gaius, feeling no hesitation at all, that he knew exactly what the dragon had meant. He still does. Sometimes he wonders what that understanding will do if he frees it from the cave, just like the dragon.
The throne room is for the big lies. Not those excuses Merlin comes up on a regular basis, like no, I have no idea why that bandit suddenly had boiled hands, and what do you mean, where's your lunch? I thought we agreed we'll keep you in shape. No, the throne room, which is soaked with Uther pronouncing judgment, announcing executions or denying requests, is for the claim of Will having been a sorcerer, for the cause of Morgana's nightmares, for the dragon's escape and all deaths that ensued, and for the worst kind of lie, the one whose truth or falsehood he is not sure about. That was not your mother you saw. Merlin still has no idea what Morgause conjured up, an illusion or the spirit of a dead woman, but he knows what he saw afterwards, and that was Arthur coming apart. That was what he had to stop. Sometimes he wishes he hadn't. Sometimes, anything looks worth Uther being dead and the ban on magic ended. But then he remembers the fear and hatred on the face of the woman who caught him shaping smoke, he imagines the knights turning against a patricide and the people blaming magic for their prince killing their king. He imagines Arthur drowning in the blood of his father, and Merlin knows he'd make the same choice again.
There is no spell he has stored in the throne room of his mind. Nothing magical. He would never. But there is the memory of poisons, every single one that Gaius ever told him about, poisons and antidotes and Morgana drawing breath after shuddering breath, slower and slower while everyone else in the castle starts to wake up once more.
The first time Merlin starts to distrust Morgana isn't when she decides to avenge Gwen's father by killing Uther, and draws back at the last moment. He's drawing back at the last moment himself at that point. It's not when the dragon starts to call her a witch, either. It's when Merlin tells her that Uther is executing people for her supposed abduction, and she still refuses to come back. Her freedom is more important to her than the people dying for it. He remembers the sense of disappointment mixed with pure envy, and that disturbs him most of all. Because it's not that he suddenly can't understand her anymore, it's that he still understands her all too well. His own moment of taking the opportunity to run, to be free and himself without any disguise, comes a few months later when he encounters Freya, and he takes it just like Morgana takes her opportunity with the druids. He tells himself it's because Freya has no one else, which is true, because he loves Freya, and he's convinced he does, but what makes him promise he'll go with her, leave Camelot, is also something far more selfish. With Freya, he would have been responsible only for one person. Not for some grand destiny, not for a kingdom. One person, and he thinks he could have done that. He wouldn't have had to lie anymore, and the fear, that every day fear of being found out, of finding rejection and hatred where it would break him to find it, that fear would have been finally over and done with. So he paints a picture of the two of them seeking freedom together to Freya, and then it ends just like Morgana's stint with the druids, in pursuit, capture and more death. Merlin looks at Morgana, sees himself and distrusts her a little more every day until the fires of Idrisholas burn, and nothing will ever be the same ever again.
You don't know, he says to Gaius about Freya, you don't know what it's like to be afraid of what you are, and Gaius looks at him, eyebrows for once not raised, and mercifully pretends they're only talking about Freya and no one else. You don't know what it's like to be a monster. He remembers Nimueh, and Cornelius Sigan, and wonders whether this is waiting somewhere in his future. For all he knows, this is what the dragon really had in mind when talking about destiny. Back to the dragon again, and the caves, like the tunnels he hid Freya in; the tunnels are for what lurks within, always.
Camelot's battlements, by contrast, are good places. Nothing but the sky above you, and sometimes Merlin wonders what it would be like to fly when he's standing there. He hasn't tried it yet, either through transformation in a bird or by making himself as light as a cloud, but he knows it's not impossible. He has read about it, he has memorized the words, and he just has to stand there to feel the longing to make them true. The battlements are for untried and unspoken things, spells and other possibilities. You can watch the knights practising from there, and remember Lancelot, getting his dream, for a little while, having to leave but with the chance to come back one day. Gaius says Merlin played God with Lancelot, setting things in motion he won't be able to control, and surely that's a bit exaggerated; at most, he has opened a door, and Lancelot was the one who walked through. But that door opening, that felt good.
The battlements are shared places, too, because mostly when Merlin thinks of himself watching for the future there, the good part of the future, he thinks of himself standing next to Arthur who is watching as well. Arthur tends to be a bit less of a prat up there than elsewhere in the castle, and maybe that's because he senses all the possibilities just like Merlin does. It's a place for truths between them, offered like on the day Merlin left for Ealdor, and of things unsaid like those untried spells. In Merlin's mind, he has told Arthur the truth in many different ways, and some of these scenarios end up in disaster, banishment, prison, or even executions, but the revelations that have good endings, the ones that lead to acceptance and maybe even more, those maybes Merlin plays out on the battlements with the past beneath them and the future ahead, and nothing around them but the sky.
Arthur's room, on the other hand, is for mundane memories. Starting with those for cleaning up spells. Because contrary to what Arthur claims, Merlin is well aware that cupboards have their uses; it's just that he thinks it would be less boring and more interesting if he varies in how he deposes the various items Arthur manages to clutter his room with in them. He's creative about it, which is altogether different from being sloppy; only sometimes when something is needed in a hurry, it's easier to mutter come a magical order for the needed item to come to him than to disturb his artistic arrangement of Arthur's possessions unnecessarily. Then there is the whole mental catalogue for hiding places (useful both to discover rats and for Merlin himself in certain situations), not to mention ways of getting Arthur into and out of his chain mail while simultaneously trading quips. Waiting to deliver a punchline until Arthur had to hold both arms raised was ever so much more effective. Not to mention that Arthur's room is the mental place where Merlin stores his ever expanding "translating Arthur Pendragon into human" dictionary. So far, he has collected four or five different interpretations for "shut up, Merlin" – it ranges from "you completely had the better argument there, and I won't admit it" via "can we talk about this another time" to "the newest assassination attempt on my life to which I am oblivious is taking place right now, so please pay attention", one definite translation for "you/I need to rest now/ get some rest now" - this invariably means "we just spoke about something important to both of us and I have no idea of how to handle it" - and is still working on the six different entries for "polish my armour". When, that is, he's not polishing said armour. If the battlements are the place for things that could be, Arthur's chamber is the place for things that are.
After finding and losing his father, after confronting the dragon and sending him away with a desperate hope for both of them, it's there Merlin finds himself, nonetheless. Of course, the castle, the real castle, not the one in his mind, is overcrowded, because all the wounded are here for Gaius to take care of. Gwen has appointed herself his apprentice and is far better at it than Merlin most of the time. Arthur was first busy organizing the transport of the knights who rode out with him and got torched for their trouble back to the castle, reporting to his father, then making sure the friends and family of those who did not survive the dragon's last attack were told. There is also the fact that the houses in half of the upper town got torched as well, which means the people stay temporarily within the keep, which, inevitably, means some thieves and hence the necessity for the remaining guards to keep watch. But now at last they're back here, and Merlin is so worn out and numb from all that happened today that he almost misses what Arthur says while he's preparing hot water for him.
"…think she is still there?"
"Morgause," Arthur says in his best put-on, pay-attention-Merlin tone, which is at less than optimum effect because he's currently fighting to get out of his boots which means he's bent over and mumbling. "Now that we're rid of the dragon, I want to search for Morgana again. I think I could find that ruin Morgause led me to the last time."
"Why should she have taken Morgana there?" Merlin asks sensibly, ignoring the pounding of his heart. "She knows this is the only place of hers you know. At best, she could have prepared a trap there, but she'll have taken Morgana somewhere else, somewhere none of us have ever been."
"I think I must have inhaled too much smoke," Arthur says, "because makes complete sense, and yet it's your voice I keep hearing, Merlin." All levity vanishes from his own voice, and he sounds as worn out as Merlin feels when he adds: "It's just – she likes games. Morgause. So maybe she could be there, and maybe I could get her to tell me where Morgana is. It's – my father misses her. So does Guinevere."
So does Arthur, of course, but being Arthur, he's unable to admit it. This is as familiar as the flickering light from the fireplace illuminating the room as Merlin puts the hot water in the bathtub. "Maybe," Merlin says, and has no idea what he hopes for; that Morgause managed to save Morgana, that neither Morgause and Morgana will be heard of again, or that Morgana will be back tomorrow and will accuse him in front of the whole court, and then there will be one less secret at last. Arthur gets into the tub, and for a while neither of them says anything. Merlin should just leave and go to his own room and finally try to sleep, or ask Gaius first whether he still needs some help.
But there is a small dragon carved of wood waiting in his room, and the awareness that if Merlin had never freed Kilgarrah to begin with, Balinor would still be alive, alone, yes, in a cave, but alive. So Merlin stays for a while longer. There is absolutely nothing magical about Arthur, no matter how his birth came to be, nor about this room, but combined they have a strange power at keeping the shadows at bay that's almost unparalleled.
"That dragon," Arthur says, eyes closed, and sounding half asleep. "When we were children, Morgana and I heard him roar sometimes. She used to wonder what it was like. To be a dragon."
Merlin lets that knowledge fill him like the magic did today, and he doesn't bother disguising the longing and regret when he replies: "It's like nothing else in the world."