Author's Note:

1. This story starts off with Merlin, and ventures into Harry Potter territory near the end.

2. This story begins in the middle of a battle with a new creature from Series 4. So I warn now...in the style of River Song...Spoilers!

3. This story just sort of came to me so I have not written a beginning as such. It begins in the middle of the action. A quick jot noted form of what's happening is a few lines below. Enjoy!

Previously on Merlin:

-Morgana opened the rift between the living world and the underworld. Creatures called the Dorocha have escaped. They look like Ghosts with skulls and suck the life out of people, leaving them a cold corpse.

-Merlin and Arthur have been battling these creatures for weeks now to no avail. Initially Merlin's magic was useless but Merlin and Gaius have now found some spells that can ward the creatures off and a possible spell to save them all. After Uther is killed by madness inflicted by the creatures, Arthur and Merlin set out to stop the Dorocha once and for all.

-Merlin, having no other opportunity, is forced to seal the rift in front of Arthur. The Dorocha stubbornly stay behind, screwing up Merlin's plan. Arthur is in shock that Merlin is a sorcerer.

And that's it. I may write the beginning at some point, but I thought I'd put this up and get some feedback.

"I can't send them back." Merlin whispered with heavy breaths. "They are resisting….too strongly."

Gwen put a hand on Merlin's shoulder for support as Arthur watched, still in shock that his manservant was a sorcerer.

Merlin fell backwards onto the cobblestone, glancing forlornly at the steadily weakening barrier. The Dorocha continued to ram the wall, sensing Merlin's weakness.

"There's only one thing I can do." He said sadly. "But I don't know if it will work."

He turned to Arthur. "You have to go." He said. "If I die, I can't risk you too."

Arthur's eyes glistened. "Merlin…" he said. "I…"

"You must!"

"No." Arthur said. His eyes turned steely as he grasped his sword. "I'm staying. You're risking your life to save my kingdom, Merlin, and sorcerer or not, you deserve to have your friend standing beside you."

The surprise in Merlin's eyes warned of the weakening of the wall as the wizard let his guard down.

"Keep the wall up, idiot!" Arthur yelled.

Merlin grinned. "Yes sire." He retorted and stood shakily. Merlin stumbled and Arthur caught him, grumbling about how the idiot was going to get himself killed.

"What do you need me to do?" Arthur asked for the first time.

"Just…no matter what happens, Arthur, remember the good things that have happened – your best memories. Don't give in to the darkness."

Arthur gulped and nodded. He glanced to Gwen. She grasped his arm tightly for fear of losing him.

Suddenly the wall disappeared and the skeleton ghosts made their way forward.

Merlin closed his eyes and whispered, "Forescieldnes." He thought of his mother cradling him as a child, hugging him before he left for Camelot. He thought of Gaius protecting him, saying "My boy!" He thought of Arthur smiling as they came back from defeating the dragon. He thought of kissing Freya.

Merlin opened his eyes to see Arthur's wide ones. A white dragon made entirely of light was dancing around the Dorocha, driving them back.

"Merlin." Arthur said softly. "It's warm."

"It's…a protector. It comes from happy memories." He said, before looking directly at Arthur and Gwen. "In order to perform this spell, I'm going to have to let them near. You'll feel cold, like the happiness is draining from you. But if you think of the best moments of your life, the things worth fighting for, they can't hurt you."

Arthur looked stoic but his eyes betrayed his terror.

"Do you understand?" Merlin asked frantically.

Arthur nodded.

"What about you?" Gwen asked.

A small tear formed in his eye and Merlin wiped it away. "I might not survive. Don't try to save me." He said, and let the white dragon disappear.

The Dorocha's shrieks pierced the air, their coldness circling all within their grasp.

Arthur and Gwen fell in a huddle while Merlin's eyes blazed a heavy gold, his words echoing in the air.

"Ásæle þá cargástas, déaþscufan."

The Dorocha circled around the warlock, trying to pierce his barrier. Merlin fell to his knees, still muttering, each word becoming more of a struggle. "Géosceaftgást, ábædan eac sælig gemyndu."

One of the shadow ghosts managed to shift through him and Merlin coughed up blood. He looked down to see Arthur's sword piercing his chest. "No…" he said. "Arthur…"

"Merlin!" Arthur exclaimed. "I'm here."

"You…" He coughed. "Arthur…"

Gwen tried to hold the real Prince back but it was useless. Merlin fell over and Arthur ran to him, sitting him up. A ghost phased through the Prince, and Arthur fell over, his body dropping next to Merlin's.

So cold…

Merlin was laughing and those golden eyes were staring at him.

"All this time, Arthur, and you didn't even think I could be a sorcerer, did you? You just thought I was an idiot, a moron who couldn't walk without tripping over his own feet. Well I was biding my time, prat. I could never be friends with a Pendragon."

He moved over Arthur and held his hand out. Arthur could feel the life draining from him, so cold…

"No!" his mind screamed. "No. That wasn't Merlin."

Then he remembered Merlin, throwing open the curtains, Merlin, insulting him, Merlin fighting the dragon with him, Merlin…all those times…Merlin.

"No!" He exclaimed, and sat up, turning to his side. "No, Merlin, wake up you idiot! You've got to finish the spell!"

He slapped Merlin's face.

"Ack! It's not bad enough that you stabbed me but now you're slapping me too?"

"Shut up Merlin, I didn't stab you, now wake up!"

Merlin coughed blood again before opening an eye. "What?" He muttered.

The Dorocha loomed overhead.

"You didn't…?"

Arthur shoved Merlin out of the way just in time to save him from the ghostly skull but ended up taking the brunt of it himself. Merlin's cry echoed with Gwen's as Arthur's skin turned blue. He took a deep breath and his eyes blazed golden again.

"Ásæle þá cargástas, déaþscufan!" He said, repeating the incantation. Merlin stood steadily, holding out a hand. He was shoved backwards by the force of repulsion of the spell but continued to shout. The spirits rammed him harder.

"Géosceaftgást, ábædan eac sælig gemyndu!"

Merlin stumbled further backwards, only to be held up by Gwen. "Come on, Merlin." She whispered. "You can do this. You have to do this."

He drew another breath. "Ic árære þes galdorléoð ábædan fram bealu. Sé friða!"

A suction noise suddenly sounded through the open air. Merlin and Gwen covered their ears as the shrieks become more high pitched, nearly painful. Dark magic sifted from the creatures and dissolved into the night.

Black cloaks circled their forms and the shrieking turned to a hiss. Bony hands protruded outward toward Merlin, but he'd quickly conjured the white dragon to protect him.

The warlock's eyes widened as the now cloaked and much less powerful creatures began to back away. He stood. "Not so fast." He ordered.

They paused in fear of the powerful warlock, hissing foreign whispers on the air. "I won't let you torment the people of Albion." Merlin said, eyes shining. "You will hide in the cave just North of the lake of Avalon. I'll come for you when I'm ready for you to fulfill your purpose."

To Gwen's and Merlin's surprise, they obeyed.

Merlin's legs finally collapsed with exhaustion and he fell to the ground, accidentally elbowing Arthur. He suddenly realized how cold the prince was. "Arthur!" He shouted, shaking him. Arthur was so cold.

Camelot was burning. Merlin was watching with glee, grinning, except that grin was so malicious, so unlike Merlin.

He's betrayed you. The whispers said. You're dying.

But it was cold, too cold for his proximity to the fires burning the castle.

"This isn't real!" Arthur exclaimed.

"Do something!" Gwen exclaimed. "We're losing him. You must know some healing magic, something."

Merlin took a deep breath, thinking. The white dragon circled overhead.

Arthur felt something warm nearby, something comforting. Was that Merlin's magic? No, it couldn't be. Merlin was watching the castle burn. But what was it?

"So warm…"Arthur muttered. Merlin's eyes widened as he glanced to the magic dragon in the air. An idea came to him.

"Gwen, I have an idea, but you need to move away from Arthur."

"Merlin?"

"Trust me." He insisted.

Gwen nodded and moved backwards. Merlin, too, shuffled backward. Thinking of all his good memories with Arthur, Merlin ordered the white dragon to retreat inside the prince.

The dragon soared downwards on its trajectory and disappeared inside Arthur's chest. Gwen gasped and Merlin bit his lip in fear as Arthur's body shook from the powerful magic.

Arthur twitched and turned and he tossed his arms. He was warm, so warm. That Merlin, that laughing Merlin…was melting? Arthur backed away as the flames disappeared, leaving the Castle intact. Merlin melted into…a skull?

"Merlin!" He shouted.

"Arthur." Merlin replied.

Merlin glanced to Gwen with nervousness before resting his eyes back on Arthur, who was regaining some color. He reached out cautiously to check for a pulse when Arthur suddenly awoke with a start. "Merlin, what was that for? That bloody hurt!" He exclaimed, cuffing the warlock round the head.

"Sorry, sire, next time I won't try to save you." Merlin retorted.

Arthur paused. "Wait. Are they gone?"

Merlin grinned and Arthur pulled him into a tight hug, laughing loudly before suddenly pushing him away with embarrassment. "Never tell anyone I did that." He ordered.

"I think…we should go home." Gwen said, and the boys agreed.

2 days later:

"I'm about to make the biggest announcement the Kingdom has had since the Great Purge and you're sitting in your new chambers writing?" Arthur exclaimed.

Merlin sighed. "I'm working on something." He said. "We can't just leave those démontorres out there."

"Dementors?" Arthur asked. "What kind of a name is that?"

Merlin rolled his eyes at the gross mispronunciation of the old language. "Demons of the tower." He said wryly.

"Tower?" Arthur asked curiously. "Does that have to do with this plan you've been working on? Is that why you're too busy to attend court?"

"Yes, but it's not ready yet." He said, about to roll up the parchment.

Arthur grabbed the blueprints before Merlin had the chance. "If it's more important than the announcement that you're my new court sorcerer, then it's ready enough."

"Hey!" Merlin protested.

Arthur looked at the tall triangular structure drawn on the parchment. The Dementors, as Arthur had called them, were drawn circling the towers.

"Merlin, is this…?"

"A dungeon of sorts." Merlin said, snatching the paper back. "To hold those who practice dark magic. I thought it was about time we put them somewhere they can't escape."

The king's eyes widened. "Merlin, you, I mean, out of everyone, you've always been the one to see the good in people. This goes against everything you believe."

Merlin sighed heavily. "You're right. I've given it some thought, Arthur, and not everyone can be redeemed. Morgana…"

He paused. "Morgana is unreachable now. What she did – she almost destroyed Albion, Arthur. Morgause, Alvarr, Mordred – they are all still out there, and no one knows where they are. But make no mistake. Even with the new laws, they will rise against Camelot. They won't see reason."

The warlock sighed. "There has been enough death. I won't kill them but I must contain them." He said with regret.

Arthur sighed too. It was a warrior's curse, to be hardened by battle and Merlin had seen his fair share. He placed his hand on the warlock's shoulder.

"What will you call it?" He asked.

Golden flecks tinged Merlin's eyes as he said softly. "Áscádan. It's the old language for separate, cleanse and purify."

Arthur looked into his eyes with sadness and said, "Don't forget about the ceremony, Merlin. You're a loyal friend, and I want the people of Camelot to finally see that."

With that, the new king left, leaving Merlin to glance at the blueprints forlornly before following him to the Great Hall.

The prison was erected in the North Sea, the Démontorres dispatched to guard it. And over the years it stayed, even when Camelot fell, when Arthur was slain, and when Merlin fell into the eternal sleep.

Then, centuries later, a single warlock found a set of preserved blueprints in the rubble. This man told no one of his discovery, and tucked the plans into the vaults below Gringotts. The land had become overrun with dark magic and so he created the Wizard's Council, and became the Chief warlock, gathering a group of followers. A year later, he revealed the prison.

The man learned the spells to protect himself against the démontorres and taught it to his council members. The council then used the prison to contain the most horrible of witches and warlocks.

And it continued to be used, even when the Wizard's Council became the Ministry of Magic, and the man was forgotten, along with the blueprints in the dusty vault below Gringott's.

Without the original documents, the names were passed by word of mouth. The démontorres became Dementors, and Áscádan became known as Azkaban, the meanings disappearing with the story of Merlin and his hidden scrolls.

At least until the day Albus Dumbledore inherited a vault, and a new story began.

This will eventually be continued but until then I'd be happy to hear what you think.

Merlin's spell translates to: [I bind the spirits, the shadows of death. Doomed spirits, to be warded off with happy memories. I create this enchantment to ward from harm. The Protector.]

The inspiration came from the fact that the Dorocha were basically really strong Dementors, and I wondered how I could spin that into an origin story for Azkaban, Dementors and the Patronus charm.