"Gaius!" The muffled shout was loud even through the door – the excitement seemed to reverberate through the wood. That could only mean one thing.

Merlin burst into the room, a smile stretching across his youthful face. Gaius might've dropped the vile of dark liquid he was holding had he not been expecting the less-than-subtle appearance.

"Gaius," Merlin said between quick breaths, "do you remember that potion you made when Uther's ghost broke through the vail? The one that tasted really rubbish?"

The old man responded with a half-hearted "mhmm."

"Do you think you could make it again?"

Gaius glanced up from his work. Merlin's eyes were narrowed with anticipation, his lips folded in. Something in the expression made his ears look even larger than usual.

The old man held up the vial. "You mean this?" he said, "It'll be done by nightfall."

"Thank you, Gaius!" Merlin said, diving towards the old man to give him a hug before remembering his clumsy manor could easily knock the sacred liquid from Gaius's hand.

Gaius raised an eyebrow. "Merlin," he said, "you do know that when you find him, you'll have to send him back."

Merlin stopped in his tracks. "Maybe," he said.

"Maybe? Merlin you can't seriously be considering…"

"Oh come on, it won't be like before. He's not his father's son. He won't hurt anyone."

"I'm not denying Arthur is of a calmer temperament than Uther, but spirits are not meant to cross into this world. It upsets the balance and…"

"Gaius," Merlin said, tightening his shoulders, "I will do what I have to if it comes to it, but it might not come to it. Maybe," – there was a tremor in his voice here – "maybe this time everything will be fine."

Gaius let out a sigh, but made no reply to the youthful sorcerer. After some stirring and mixing, he said, "come back tonight and the potion will be ready."

IOIOIOIOIOI

Merlin returned when the shadows in the town were growing long and thin. Gaius was hunched over one of his big wooden tables, studying the liquid in the vial with a curved piece of glass to make sure the consistency was perfect. Merlin bounced up and down on his toes.

The day had passed in a strange haze. George had spent some hours in the afternoon following Merlin around the garden, half-listening to Merlin's explanations of the properties of herbs and half trying to slay slugs and other slow-moving bugs. He seemed entirely unaware of the presence that followed them around, haunting the grounds with a quiet vibration.

Aithusa, on the other hand, had been on edge all day, all too aware that something was different in Camelot. She paced the courtyard discontentedly, occasionally stopping to focus with rapt attention on some nothingness in front of her. When Merlin caught her doing this, he would look too, willing himself to see what she saw, to confirm his suspicion.

Once, right before supper, an overripe apple had fallen from a tree and landed Merlin square on the head. He groaned and rubbed his head, and very nearly said, "Arthur you clotpole!" but stopped himself for fear it really was just a rotten apple and he'd be making a fool of himself.

A fool in front of whom he wasn't sure, because he was perfectly alone. Still, he wanted to be certain.

Now that dusk was upon the land and the potion was nearly ready, Merlin could not contain his anticipation one moment more. "Gaius, is it ready yet?"

"Patience," Gaius said, and Merlin was certain he would follow the word with some epitaph of wisdom, but the old man simply grew quiet and Merlin was forced to wait on in silence. He took to pacing around the room, lighting the candles to combat the fading day. When the last candle was lit, Gaius made a show of straightening himself up and holding the vail up to the flickering orange glow.

Both men stared at it for a long while, and then Gaius presented it to Merlin.

"Don't drink it all," Gaius said, "Half should do. I don't know how long it'll last. It's more potent than the last batch, if I'm remembering correctly."

"I wouldn't drink a drop more of this than I had to," Merlin said, "if it's half as bad as I remember it."

"It'll probably be twice as bad."

Merlin took a deep breath. "Well, bottoms up." And with that he knocked back half of the liquid in the vial in one foul gulp.

The candles suddenly blurred into masses of yellow-oranges and whites, and Merlin blinked through what he thought must be tears. He felt like his feet had left the ground, and that he was possibly standing on the ceiling, but he knew this to be false: he was where he stood and that was the end of it.

Gaius squinted at him. "Are you alright?"

"It's definitely potent," Merlin rasped.

"Sit down," Gaius said, waving Merlin toward a bench. Even as he refused Merlin felt himself moving toward the chair. He sat.

"I think a quarter vial would've done."

"I'll dilute what's left," Gaius said, taking the vial from Merlin's shaking hands. Slowly the world stilled itself and Merlin could see clearly again – too clearly, as it were. He could see the essence of each thing in the room, shimmering around it like an aura. This was what it took to see a soul.

IOIOIOIOIOI

Merlin tip-toed through the castle. Night had settled in the time it took Merlin to regain his footing well enough to begin his mission. The sounds of water sloshing in buckets and pans clattering together rose from the kitchen, announcing the servants' final cleanup. George had long been put to bed, and only Aithusa stirred in the courtyard below. Camelot was at peace.

Merlin glanced out a window at his dragon, hoping to glean something about the ghost he sought, but her behavior was normal and told him nothing.

A rustle of the wind brought Merlin down to the locked door of the armory, and thinking he heard something within he whispered a spell and the door swung free. He stuck his head inside but found only moonlight glinting off swords, shields and crossbows. He took a step back and bumped into something, or rather someone. "Arthur?" he whispered.

"What was that, Sir Sorcerer?"

Tristan.

Merlin glanced over his shoulder at the young knight, who was smiling back so fiercely that Merlin wondered if his cheeks didn't burn from the effort.

"I didn't say anything," Merlin said. He pointed to the knight. "Did you?"

"No, I just said…" Tristan careened around Merlin's head to peer into the armory. "What are you doing in the armory, Sir Sorcerer?"

"I've told you, it's just Merlin."

"I could have sworn I locked that door," Tristan said, tapping a long, spindly finger on the keyhole. His eyes grew wide, "Did you use magic to open this door?"

"I…"

"That's amazing. You can just unlock anything? What is that like? Wait, why did you unlock the armory door?"

"I was," Merlin mumbled, "looking for ghosts."

"Ghosts?"

"Sure," Merlin said. After thinking for a moment, he leaned in and whispered like he had a secret. He said, "The armory is always loaded with ghosts. What do you think happens to all those people who get killed with these swords?"

It was hard to tell in the blue light, but it looked like Tristan had suddenly gone even paler than usual. His face contorted into something like fear. "Really?"

"Of course. I was just doing a routine check on the weapons, to make sure there are no ghosts attached."

"And?" Tristan prompted.

Merlin ineptly looked around the room. "Looks like you're all clear. No ghosts here."

"Oh, thank goodness." Tristan said. As Merlin swiveled back to face him he caught a glimpse of something quick and golden passing around a corner. "I don't know what I'd do if I saw a ghost."

"No, I don't know either," Merlin said. "Excuse me, Tristan." With that, Merlin slunk away, calling back to Tristan to remind him to relock the armory. The young knight stood for a moment, watching the sorcerer go, and then went about fumbling through a set of brass keys to find the right one.

IOIOIOIOIOI

Gwen lay awake in bed, staring at the canopy overhead. The purple flowers bloomed by her bedside, and she couldn't help but feel uneasy despite Merlin's reassurances. She sighed, rolled over, sighed again. There was nothing that could still her churning mind, and so she quietly rose and threw on some dressing robes. A walk, she thought, might do her some good.

IOIOIOIOIOI

Merlin followed the something golden down a long corridor and up several flights of spiral stairs. Every time he began to question the accuracy of his steps, he would again catch a glimpse of that ethereal light he sought. Eventually this endeavor lead him to the middle of a long stone hallway, where Merlin stood in the flickering torchlight and waited.

A long moment passed. It grew longer. He nearly resolved to move on, when the air suddenly took on a bitterness to it, and Merlin felt a shiver run up his spine. The torches lining the hall all blew out at once in a flurry. Merlin stood in the darkness for half a second, his mind racing, then he whispered a spell and a little orb of light formed in his palm. He held it up light a candle.

"Arthur!" Merlin called.

Behind him, Merlin heard something stir, but he didn't move.

"Scared, Merlin?" came the steady voice of his king.

"Me, scared?" Merlin said, "Never."

The sorcerer turned and found Arthur smiling behind him, arms crossed over his chest and a smug look on his face. The men regarded each other, each brimming with a strange yet familiar happiness.

"Seems George is a bit more like his father than he realizes," Arthur said. "Tell me, Merlin, did you have to drink that awful concoction of Gaius's?"

"It's even worse the second time," Merlin said.

Arthur laughed, deep and hearty. The sound reverberated down the long corridor, and Merlin wondered if anyone else could hear it. He almost hoped the rest of the castle could hear that sound, that hopeful, wonderful sound.

"Did you see Gwen?" Merlin asked.

Arthur nodded. "She looks well. A little sad."

"Well, you know what day it is."

"I do know," Arthur said, "And I remembered all on my own. You didn't even have to remind me this time."

"First time for everything, I suppose."

Arthur moved to bump Merlin on the shoulder, and Merlin was surprised when he felt it. Arthur was more than just a trick of the light. He had substance.

"Is it good to be back?" Merlin asked, "In Camelot?"

Arthur looked around at the darkness that surrounded him. "It hasn't changed much," he said slowly, "but I know it is no longer mine."

Merlin shook his head. "It will always be your Camelot, Arthur. Ask anyone."

"Unfortunately it looks like I have only you to talk to," Arthur said, raising an eyebrow. "A fate worse than death," he added playfully.

Merlin opened his mouth to make a witty reply, but the soft sound of footfalls kept him silent. Arthur looked at him, and Merlin quickly doused his ball of luminescence. The hall fell into total darkness.

As the steps drew nearer, so did the flickering of a candle. A yellowy face danced above the flames – Gwen, out pacing the castle in search of some relief from her insomnia. The light of her candle didn't catch Merlin until she was nearly on top of him, and his sudden appearance out of the darkness caused Gwen to let out a little shriek.

"Merlin," she said, one hand folded over her breast while the other clenched the base of her candle. "You startled me. What are you doing down here in the dark?"

Merlin glanced at Arthur, who was still by his side. The King had his head bowed and his eyes fixed on the floor, as if his not seeing Guinevere might prevent her seeing him. Oddly, this seemed to be working well enough, at least in the sense that Gwen couldn't see him, though Merlin suspected this had nothing to do with the aversion of his gaze.

"Gwen," Merlin said. He fumbled.

"Do not say you're checking the castle for ghosts again," Arthur ordered.

Merlin glanced at Arthur and then back to Gwen, who was staring at the befuddled sorcerer with a look of concern.

"I am," Merlin said, "doing what you're doing."

Gwen's hand dropped from her chest and she sighed. "You couldn't sleep either?" She paced a few steps, so that she was close enough to Arthur he could feel her breathing. Gwen tensed up, though she herself didn't seem to know why. "I just feel there is a restlessness in the castle tonight."

"Oh?" Merlin said.

"Like something has changed this day."

Merlin side-eyed Arthur, who was now looking intensely at Gwen. "Don't tell her," Arthur ordered.

Merlin wanted to ask, Are you sure? But saying anything at all would give Arthur away.

"Perhaps," Merlin said, "Your memories of the past have been stirred today. Perhaps the restlessness is only yours."

Gwen considered this, and Arthur reached out a hand to touch her hair, but refrained. Instead his pale, yellowy fingers fluttered just above Gwen's curls. Merlin bit his lip.

"You're probably right, Merlin," Gwen said. "I forget sometimes how powerful memories can be." She smiled and touched Merlin's arm in farewell, and then slipped back down the corridor the way she had come.

"Sometimes I forget, too," Merlin whispered.

Arthur's hand still hung suspended in mid-air as he watched the love of his life fade into the night. The look in his pale blue eyes made Merlin desperately want to turn his back, but he couldn't stop watching his king watch the queen walk away.