Cas POV

Cas had known from the start it was a bad idea to let them go on a holiday but the Winchesters had insisted on it. They hadn't had a proper holiday in their entire lives so he supposed they deserved one but all the same he knew it would never work out well and now they were in trouble and he couldn't find them. For a place so small, England was so busy and hard to understand. This was another reason he had not wanted them to come here but no matter what he said, Sam insisted that it was a good idea. At first Dean had been on the angel's side; mostly because the only reason Sam wanted to go was because it sounded like a cultured, interesting place which isn't exactly high on Dean's list of important things, but when Sam told him that "English girls were hot and had a thing for bad American guys" he changed his tune, and finally the angel buckled and let them go.

Despite Sam's determination that nothing would go wrong, Cas knew something had when he saw them on the news being dragged into police cars for "vandalising public artefacts". Apparently they broke into a famous museum and burned one of the artefacts belonging to an Egyptian pharaoh. Cas did wonder why they hadn't alerted him when they discovered a case but since he'd come to England his angelic powers seemed to keep stopping working periodically at random points throughout the day, so he supposed that was why they'd never been able to get through.

So instead he had resorted to wandering round London looking for somewhere that looked like what he'd seen on the TV. From what he'd heard London was described as a fairly densely populated place but where he was there were very few people at all.

"Excuse me sir," he said to the first person he found. He was quite a young man, but with old eyes and he was sitting on a bench staring out across a lake opposite. When he heard Cas' voice he looked up quickly, a hopeful look on his face then tried to hide his disappointment when he saw him.

He put on a very fake smile which Cas was sure didn't mean to appear so unwelcoming, he could tell this man was lonely and waiting for someone who didn't appear to be coming. "Yes?" he replied.

"Have you seen two tall, fairly muscular American men around here recently? They might have been being arrested or alternately they might have been running around with guns, salt, iron or shouting in Latin?" Cas asked with a deadpan expression.

This time the man gave a genuine smile. "You're joking right?" Upon seeing the serious look on Cas' he realised he wasn't. "I haven't seen anyone like that round here, sorry."

He frowned, realising he must be in the wrong place. "Thank you sir."

The man smiled in response and went back to staring out over the lake. He looked back up a few seconds later but Cas was already gone. It had taken the angel an extraordinary amount of power to pull away from that place for some reason, but that didn't matter for the moment because he had summoned enough strength and had found Sam and Dean.

After rescuing them from a possessed police officer Cas sent them both back to their hotel to rest, because he had something to do now. What could possibly have enough power to match an angel? It was fairly easy to find the source of it, since he could almost feel himself being drawn there, even now.

When he reappeared he found himself outside a lonely looking cabin in the middle of the woods. The lake he had spoken to the man next to earlier could be seen in the distance through the trees and the man himself was inside the cabin, although Cas could not see what he was doing. He decided that maybe this man knew something; after all he had seemed strange, although he couldn't put his finger on why.

After spending a few moments thinking, Cas decided just to knock on the door and ask him outright if he was doing this, but as he reached out his hand towards the door it was pulled open from the inside and he felt something sharp and metal pressed against his chest. It was a sword.

"Who are you and what do you want?" the man asked him harshly.

Cas was shocked for a moment. He was used to people threatening him, but he had no idea why this man had a sword in the 21st century. Nevertheless he still went ahead with his plan. "My name is Castiel and my powers are being limited by something or someone in this area. I came to ask if you knew anything about this. Be warned," he added in case the threat was needed, "if you try to lie to me I will kill you with a click of my fingers. I also feel compelled to inform you that a sword would do you little good."

The man looked taken aback by Castiel's straightforward approach. "Look I'm the only person who lives anywhere near here and you really don't need to put on this whole "invincible" act because I don't think you're much of a match for me. As for your "power" I have no idea what you're talking about. If you mean phone power or something like that I keep telling people I can't help it, it's just the area we're in that's all."

"I do not speak of cell phone power, I mean my own powers. Since you are the only person here I must assume it is something to do with you, so tell me how you are doing it." Cas demanded.

"Doing what?" the man sounded completely bewildered, "I have no idea what you're talking about but maybe I can help you." He held out his hand, "I'm Merlin."

Suspiciously Cas accepted his handshake but as their skin made contact he felt a huge surge of energy through his body; an energy he recognised as magical.

Castiel looked surprised, "Do you practice witchcraft Merlin?" he asked.

Merlin looked angry all of a sudden. "Look if you're part of that conspiracy group, I keep telling you there is no such thing as magic and I am certainly not evil. Just leave me to live in peace."

Cas was confused now, "I am not part of any group but someone has been draining my powers and I believe it is you. You cannot lie to me, I can feel the magic in your blood; it is stronger than I have ever seen in my very long life. What did you have to do for that kind of power?"

Merlin was speechless. He stared at Cas in shock for a second before lowering the sword and gesturing for him to come into his house.

For a witch his home looked so ordinary, if slightly medieval. In fact there were very few modern devices and almost nothing that ran off electricity.

"Who the hell are you?" Merlin demanded.

"My name is Castiel," he repeated, "but most people seem to call me Cas. I am an angel of the lord and my job is to protect the Winchesters, Sam and Dean." Suddenly he had an idea. "Is that why you have been preventing my abilities? Because you will never hurt them while I am on heaven or Earth."

Merlin was still staring with his mouth open. "An angel of the Lord?" he asked in wonder. "In all my years…." He seemed to be talking to himself.

Now he spoke to Cas, "look I'm sorry if I'm restricting your powers but it's not intentional I swear." Cas waited for further explanation. "Okay so I do have magic you're right, but the reason I live out here is- well partly because people get a bit freaked out by a man who never ages- but mostly because I have this effect on things. It was no problem where I'm from but here… See if I use magic anything electrical in the area goes haywire until I stop, and if it's close enough I don't even need to be doing magic, it just breaks."

Cas seemed to understand now, even if he didn't 100% believe it. "So you're saying it's affecting me how it does with all these devices only worse because I'm stronger."

Merlin nodded and Cas continued, "I suppose that's why you live like this then." He pointed around the room.

Merlin shrugged, "Partly. It makes me feel more at home too; hence the sword. I don't even need it to defend myself, it just reminds me…" he trailed off into his memories for a moment before coming too again. "So do you believe me now? You know, that I'm not an evil angel killer right?"

Still Cas hesitated. "How are you so powerful? Even now I don't understand. I've never met anyone nearly as strong as you."

Merlin sighed like he'd heard that question a thousand times. "I'm different to everyone else with magic like you said. I was born with it; it's just a part of me. Have you ever heard of Emrys?"

Now it was Castiel's turn to be shocked. "You are Emrys? I heard stories of him when I was still young but as I grew older I assumed they were just stories, but now you're real! I never would have believed it if I hadn't seen you with my own eyes."

For the first time in a long time Merlin actually laughed. "And I've been hearing stories about angels since I was a baby, but after such a long time you stop believing in things unless you've seen them. I guess we were both wrong."

Cas smiled too and there was a moment's silence before he asked another question. "How old are you? Because I know you're old, I can see that in your eyes."

"I was born in Camelot, at the time when Uther was King; you know the stories, I served Arthur until he became King after Uther, and when Albion needs him most Arthur will live once again." Merlin smirked to himself. "You know, for so many years I've been hearing the story of Arthur and I and our lives and I've heard it retold so many times and in so many different ways sometimes it feels like it was all just a dream." Cas nodded, he could relate. "Usually people think of me as an old man with a long grey beard, because that was how I used to disguise myself when I didn't want to be recognised, but the way they show Arthur is quite accurate. Only, they make him sound a lot nicer. In real life he was a bit of a prat. He never realised I had magic until I told him on his deathbed." He seemed to be speaking to himself more than Cas again but the angel didn't mind.

"You know," Cas told him, "you remind me of myself just a few years ago. You're old and you're waiting and you don't know exactly what for, but you know your life won't have really started until you find it- in your case him- again. I spent so many millennia in heaven watching humanity, but my life never really had a purpose until I met Dean. I had to drag the idiot all the way out of hell, literally, but it was worth it. Arthur will come back when it's right and no matter how long you wait it'll be worth it, I can promise you that Merlin."

"Thanks Cas." Merlin smiled to his new friend, but before he could carry on the angel gained a look of intense concentration before speaking again.

"I'm so sorry Merlin but I'm going to have to leave. Sam and Dean have been trying to get through to me for about ten minutes, something about a witch; an evil witch- not your kind." After seeing the sad look on Merlin's face he added, "I'll come back and visit, I give you my word."

With an extreme amount of effort Cas managed to pull himself away from there and back to the Impala where he faced a ridiculous amount of questioning from the Winchesters.