Voila, I've decided to try my hand in a Merlin and Harry Potter crossover. I've been considering it for a really long time and so on since Merlin absolutely rocks and all that. As such I'd really appreciate commentary on my writing and if I've stayed in character and all that. Thanks

Disclaimer: Saying it only once, own nothing.

WARNING: Merlin and Arthur slash and kissing and all that (MEANING, MALE/MALE). You have been warned.

Chapter One: Merlin

Merlin paced the length of his apartment, situated in Baker Street, London. More specifically, it was his and Arthur's newest apartment that Arthur had insisted they buy some five years ago. The large window in the living room provided Merlin with the perfect view of the grey clouds and constantly busy streets of the area so different from Camelot and even more so for Ealdor. Yes, the twentieth century sure was different from where Merlin had grown up. Silently, Merlin had always speculated that the only reason why he and Arthur were able to adjust so well to the present was because of their immortality that had allowed them to witness and be part of the changing world.

At first it had only been Merlin who was immortal, a fact discovered by Gwen when she'd made the harmless comment of him still looking so young while they all aged. After some research, they'd discovered that it was the power of Merlin's magic and its proximity to the Old Religion that was the cause. It had been strange, seeing the world go by while he stayed young, suspended in time for eternity.

But luckily, he had not been doomed to live out forever on his own.

It had all started with the Battle at Camlann, when Arthur had gone into battle, completely ignoring Merlin's terrified protests in favour of bringing justice to the world. Merlin had followed him into battle, at his side like always, and had been about to defeat Morgana when Arthur had been struck my Mordred. Merlin had never felt more horror than that moment when he watched Arthur fall, Mordred's sword protruding from his back. Merlin, in a fit of rage, had thrown both Morgana and Mordred aside and rushed to Arthur's side, transporting them to the Isles of the Blessed where he proceeded to beg for Arthur's life like never before. Unfortunately, like many times before, the Old Religion was unwilling to take Merlin's life so Arthur could live and Arthur might have stayed dead forever had Morgana not arrived.

Thinking back, it could be nothing short of ironic that the person who was so bent on destroying Arthur, would be the one to save him. Merlin had acted out of instinct, killing Morgana with words he would later be unable to recall and, like a miracle, Arthur had woken up from the dead, Morgana's life in exchange for Arthur's. It was only later that Merlin would come to realized that he'd somehow tied his and Arthur's souls together, stranding Arthur in the same ageless state as Merlin.

Unfortunately, Camelot could not be saved in the same manner and the great kingdom fell soon after, driven into the ground by its own people. The whole of Albion collapsed in on itself while Merlin fled with an unwilling Arthur.

For seven long years Merlin was convinced that Arthur hated him since, after their escape from Camelot, the king had disappeared from his life, leaving Merlin to live in regret as he convinced himself that Camelot's downfall had been his fault.

It had been far from pleasant as he pondered whether he could've saved Camelot if his magic been stronger, while another part of his mind constantly wondered over the health of his king. Still, Merlin did not try searching for his missing king, afraid of the anger he would have to face if he found him. Now though, Merlin dreaded to think how much longer they could have been separated had they not met again, practically in the middle of nowhere only to later find out that the bond that had been created after Arthur initial death, had been the reason for them finding one another once again.

It took time, but Arthur had reluctantly come to terms with Camelot's loss and had agreed that they needed to stick together since they were all that was left of their old life.

Strangely, living an eternity with Arthur hadn't been as difficult as Merlin had first suspected it would be, but that was quite possibly because they were already so used to each other's quirks. Not to say they didn't fight, but it didn't feel as if anything had really changed between them. Well, Merlin considered, there was one thing and that was the fact that Merlin had realized he loved Arthur in a none-plutonic way.

When Merlin first came to notice his developing feelings for the former king, he'd truly tried his best to deny them, terrified of losing Arthur if were to find out. He'd done a good job of keeping Arthur in the dark for the most part but somewhere along the line Arthur must have lost his obliviousness since he started questioning Merlin about his relationships and romantic interests, practically getting Merlin to confess, to Merlin's greatest horror. The confession had been followed by two nights spelt locked in his room while Arthur schemed behind his back. On the second night, he broke into his room and kissed Merlin awake, the only person in the world who could've succeeded in such a scheme since Merlin's magic was unguarded towards Arthur. Even so, it had taken Arthur a few speeches to convince Merlin that he truly did feel the same way towards him.

After that, they'd gone from publicly married to posing as brothers, whatever was acceptable at the time. But as long as they were together, Merlin found he really didn't care.

Of course, as the time passed, the world changed and magic along with it, growing weaker over time.

Merlin had been distraught when the humans used this to their advantage and started forcing sorcerers, or wizards and witches as they were now called, into hiding once more, effectively destroying all he and Arthur had worked so hard to build. The sorcerers in turn, had retaliated and Merlin had changed into his Dragoon form one last time in an effort to force peace between the human, now known as muggle, world and the sorcerers' world. Unfortunately that had resulted in Merlin being forever known as an old man with the white beard and long hair instead of the reality of his permanent youth. Arthur had of course teased him endlessly for it.

Merlin's last input, though unknown to anyone else, had been to build Hogwarts with the Founders since both he and Arthur had agreed that they couldn't allow anything else to be built on the ground that had once supported the great city of Camelot.

Despite it all, it seemed that their peaceful life would soon be disturbed if Merlin didn't take matters into his own hands, a decision that had not gone down well with Arthur but that he had eventually conceded to, promising that Merlin would owe him big time when it was over.

Merlin wasn't too fazed, knowing that, despite what Arthur said and pretended, he also wanted to do something to help rid the wizarding world of the murder known as Voldemort.

The sorcerer had immerged some twenty five years earlier, bent on purifying the wizarding world of human-born wizards and witches. Back then, Merlin had been set on going out and destroying the man but his gut had stopped him, an indication from the magic of the Old Religion that he should stay put. Merlin had relented but Arthur hadn't been so easy to convince. So they moved to Africa, disguised as normal humans while they watched the wizarding world war from afar.

For eleven years he and Arthur watched, from a distance, as human and human-born alike were slaughtered and threatened until, by some miracle, Voldemort vanished: Banished by a year old baby named Harry Potter, the boy who lived.

But it was not to last.

It had been a few months back that Merlin received the vision, coming in a dream like they'd always done with Morgana, and Merlin had heeded the warning. Voldemort was coming back and they could and would do something about it.

So he and Arthur had lain out a plan and were quick to execute it too, sending in a request to attend Hogwarts as students for the coming year or more if need be, so they could keep an eye on everything while undercover. Merlin had never been so glad that the circumstances of Arthur's birth allowed Arthur the ability to wield a wand, or maybe it was that he and Merlin's souls were now connected, but either way Arthur was able to practice this weaker form of magic. That at least allowed him to be part of the wizarding world as equally as any other wizard, with the exception of having Merlin as his mentor. It also meant that Merlin wouldn't be forced to attend Hogwarts on his own.

Still, delaying Voldemort's return was completely up too Merlin since he'd realized that having Arthur there would only complicating things and possibly put Arthur in unnecessary danger. Of course Arthur had felt the need to throw a tantrum when Merlin had informed him of this, stubbornly denying it when Merlin pointed out that Arthur seemed to be worried about him.

Now though, Arthur was sat on his fake leather chair – Merlin insisted that they stop buying real leather the second it had become a possibility – scowling slightly as he watched Merlin pace. Merlin knew Arthur hated it when he showed his anxiety but he couldn't help it. Merlin's mind had been on edge all day and his gaze was constantly wandering towards the clock on the brick wall.

Only a few more minutes to go.

"Damn it Merlin, I've changed my mind. I'm not letting you go!" Arthur finally snapped, shooting up from his seat.

"Don't start with that again!" Merlin shot back, pausing in his pacing to glare at Arthur.

"You're not leaving and that's final," Arthur stated, folding his arms over his chest stubbornly, determination glinting in his eyes.

"Don't be ridiculous Arthur, if you don't let me do this, the whole wizarding world will suffer, it's like asking me not to give my life up for you if I have to," Merlin reminded with an agitated roll of his own eyes, the strangeness of his second declaration had worn off decades ago.

"I can't lose you Merlin," Arthur insisted, his voice was as passionate as ever but Merlin couldn't let himself be swayed, instead simply closing his eyes when he felt Arthur's arm encircling his waist and savouring the familiar feeling of his husband pressed up behind him.

"You know I can't let this happen, I won't fail again," Merlin murmured as he turned around slowly lowering his head so he could bury it in the crook of Arthur's neck while trying to block out his memories of Arthur's death.

Pulling himself away from the memories and glancing once at his wedding ring for reassurance, Merlin turned back to the task of convincing Arthur.

"It is my destiny to protect you Arthur and I will do so to my dying breath but I'm the embodiment of magic as well and the Old Religion put me here to help. I'm not just here to play your personal servant." his voice was gentle, almost reassuring but it still left no room for argument. The last part however, was added in a joking tone as he tried to make light of the situation.

That said, Merlin glanced over at the clock before placing a chaste kiss on Arthur's half opened lips, pulling back to study his husband's face with an intense gaze that eventually forced a reaction from the former king. "Don't look at me like that, I'm not a child I can take care of myself!" he exclaimed, pulling back and folding his arms stubbornly once more, the perfect picture of a pouting child.

"You still have to convince me of that, besides, this shouldn't take more than five minutes at the most!" Merlin grinned.

"So if it does then I should start worrying?" Arthur questioned with a raised eyebrow, his voice giving no indication as to how he was feeling.

"Arthur! I'll be back before you know it!" Merlin's voice conveyed his exasperation as he stared at his husband imploringly.

Arthur didn't respond and Merlin bit his lip, suddenly realizing just how worried Arthur really was about him. It had been centuries since they took part in anything dangerous even though Arthur insisted on them practicing their sword fighting, self-defence and magic every week.

"I'll be safe, Arthur, I swear," Merlin promised, his voice serious once more.

"I'm holding you to that," Arthur replied, his voice formal and strained with his hidden emotions.

Nodding, Merlin turned to the clock and silently counted off the seconds before his eyes flashed and a wind whipped into existence, a transportation spell long forgotten by modern-day sorcerers.

The world started spinning around him and in an instant he was stood in the centre of a labyrinth, the dark green walls of the hedges surrounding him and a pedestal stationed a few feet away from him. The sound of approaching footfalls jerked him back to reality and his magic sprang into action his eyes flashing gold as time bent to his will, slowing down considerably to accommodate him.

Lifting his hand he felt his magic surge up inside him, coming to rest at his fingertips, ready for his next action.

"Afierran bealo" the words fell easily from his lips, more powerful than anything left in human memory. As expected, his magic flared out, eliminating the second transportation spell and leaving only the well-intended spell to stay. Moving his still outstretched hand, Merlin aimed it elsewhere before repeating the spell. A cry of pain quick reached his ears, confirming that he'd hit his target, and his would be attacker flew into the air.

In his mind's eye, Merlin watched as the man landed outside of the maze, in front of a crowd of people who gasped at his harsh landing. As they and Merlin watched, the man's appearance changed from that of an old man to that of a sick-looking, young on, his wooden leg and magic eye obviously not needed for his true form.

Coming back to himself, Merlin allowed time to take its natural course as wind whipped up around him once more, taking him away from the maze before the footfalls breached the middle of the maze.

Merlin gasped as he landed back in the apartment and was immediately envelop by Arthur's warm body as his husband hugged him.

Merlin breathed a sigh of relief and closed his eyes as he felt Arthur's finger in his hair, massaging his scalp in a way that told Merlin that Arthur was actually trying to calm himself. Smiling at this realization, Merlin allowed his body to melt into Arthur's, contenting himself with simply being held till Arthur felt ready to let go.

When Arthur finally collected himself enough to pull away, Merlin offered him a cheeky grin, rolling his eyes in mock exasperation.

"I told you I'd be fine," he said, his voice as exasperated as his eye gesture.

"Because your always, fine, aren't you Merlin?" Arthur questioned, his voice back to the sarcastic and cocky tone Merlin was used to and that he'd strangely come to love.

"Prat!" Merlin accused before turning and jogging into their bedroom, immediately recognizing the devious look in Arthur's eyes and knowing that nothing good could come of it.

Well, there you have it, my first chapter, more explanations about Merlin and Arthur soon to come so don't worry. Please review and tell me what you thought of it, thanks.