Disclaimer: I don't own 'Supernatural' or 'Merlin'; they belong to their respective creators, and I'm just borrowing them for this story

Feedback: Always a pleasure

The Cup of Life

"You sure about this, Cas?" Dean asked, as he and Sam walked along the streets of Camelot towards the house that they had been informed was where Merlin stayed with Gaius, the elderly court physician they'd met on their first day in Camelot. "I mean, we've dealt with the latest wave-"

"And more will undoubtedly come if we do not take action now," Castiel said, looking solemnly at his friends as they walked. "As I observed earlier, I have identified the cause of these attacks, but I will require Merlin's aid to halt it; as it stands, he cannot perceive it and I cannot channel my power in the appropriate manner to undo it."

"And... you're sure that telling him the truth is all right?" Sam asked. "I mean... well, this is Merlin-"

"Which means he's pretty used to keeping major secrets," Dean added, looking over at his brother with a slight smile. "I mean, Cas already told us he's been keeping what he is quiet since he got here; if we can't trust this guy, who can we trust?"

Sam wasn't sure if it should be considered strange that he fully agreed with Dean's point without fully understanding how his brother had come to that conclusion.

He got why he felt that they could trust Merlin- greatest wizard of all time, notorious for doing what he could to help others, that kind of thing-, but that didn't explain why Dean was being so accepting of it, after all those past occasions where Dean was the one willing to shoot the supernatural first and question what it was later...

Then again, Dean had been out of the game for a year, and they were in an unprecedented situation even for them; Sam supposed that some patience wasn't exactly a bad thing, after all.

It was the morning after their fight with the Hellhound and the Manticore, and with the other knights still resting to recover from the long night of waiting, the Winchesters and Castiel had decided to take the opportunity to talk with Merlin about the spell that Castiel had detected the night before, as well as their own reasons for being there if the opportunity arose.

Personally, Sam was hoping that they'd manage to get the job done as quickly as possible- tell Merlin what they were dealing with, get him to the future, and get him home-, but he knew that it couldn't be that easy; things never were...

"Easy..." Sam said thoughtfully.

"Huh?" Dean asked, looking at his brother in confusion. "What was that?"

"Just... I had a thought about us getting Merlin's help with this stuff," Sam said, looking between his brother and their friend. "Maybe we just... don't tell him about the time travel thing?"

"What?" Dean asked, looking at Sam in confusion. "Are you forgetting the part where we need him to destroy the Cup in our time-?"

"I mean, the demons have the Grail- the Cup of Life, whatever- somewhere fairly out of the way, right?" Sam explained, holding up a hand to stop Dean's counter-argument before he looked over at Cas. "Couldn't we just teleport Merlin to wherever the demons have the Cup after explaining that we need his help, have him do whatever he needs to do, and then take him back, without mentioning that we're from the future or letting him see something about the future?"

"It is... possible," Castiel said, nodding thoughtfully at the younger Winchester. "There is no record that Merlin had any contact with the Cup of Life after Morgana and Morgause's attempted conquest of Camelot, so no harm would be caused by him believing it to have been destroyed in this time; if anything, it may even ensure our world will come to pass, as Merlin will have no reason to look for the Cup if he believes to have been destroyed already."

"Worth a shot, anyway," Dean said, shrugging slightly before he indicated the path in front of them. "Well, let's get going; sooner we do this, happier I'll be."

After another few moments of walking through the dirty streets, they found themselves standing in front of the physician's house, the three men exchanging brief glances before Sam knocked on the door.

"Yes?" the old man they'd been introduced to as Gaius said, opening the door and looking at the three men in slight surprise. "Good morning, Dean, Samuel, Castiel; what are you doing here?"

"Well..." Sam began, suddenly uncertain how to explain his presence there.

"We need to speak with Merlin on an important matter," Castiel said, attracting a brief stare from the Winchesters before his own stare quietened their initial protests; they might doubt Castiel's social skills at times, but in a situation like this Dean in particular felt comfortable assuming that the angel had a reason for making that kind of request.

"Merlin?" Gaius said, looking at this in surprise for a moment before nodding uncertainly. "Well... come in, then."

With that said, the Winchesters and Castiel walked into the small house, their eyes quickly falling on Merlin as he stood behind a desk, looking inquiringly at them.

"Oh... hello," he said, looking awkwardly at them, clearly confused about what they were here to talk to him about. "What can-?"

"Merlin," Sam said, looking firmly at the younger man, "we know you have magic."

"What?" Merlin said, his eyes widening in shock before he tried to laugh as though he thought they were just joking. "Th-that's-"

"Trust me, it's not," Dean said, looking firmly at the other man, ignoring the shocked stare he was receiving from Gaius; if they said their piece quickly enough, that would be all the explanation Gaius needed about their reasons for being here. "I get why you're worried, but you don't have to be; we're not here to... do anything to you... and God, that sounds weird just when you say it like that..."

"Excuse me?" Merlin said, looking at the three men in confusion, his initial shock shifting to confusion as he began to process that none of the three men before him were attempting to attack him for his magic. "But... look, what makes you think-?"

"It's a long story that we can't really explain right now and you probably wouldn't believe even if we did," Sam said, looking apologetically at Merlin. "But the short version is... well, Castiel brought us here because we need your help."

"And... what makes him-?" Merlin asked (Dean had to give the kid credit; evidently he was used to or prepared to try to deny his secret if he was ever confronted about it).

"I am what you would call a Celestial," Castiel said.

"A warrior of the Creator..." Gaius said, his eyes widening before he stepped back, inclining his head in a sudden bow.

"A what?" Merlin asked, looking between Gaius and Castiel in confusion.

"A Celestial, Merlin, is one of the highest and purest of all magical beings," Gaius said, looking sharply over at the younger man. "Created by the Creator of all things as his first and most powerful creations, the Celestials were said to possess power and wisdom beyond what any mortal man could achieve, initially serving as his children before they became warriors against the darkness that one of the first Celestials created in an act of revolution."

"There were other beings involved in the creation of monsters, but your essential summary is correct, yes," Castiel said, nodding in confirmation at Gaius. "Your knowledge is... impressive."

"I studied magic for some time when I was younger," Gaius said, smiling slightly at Castiel. "It has been many years since I performed it regularly, but I still possess a broad knowledge of most fields of magic; Celestials were not one of the most prolific of subjects, but they were one of the most fascinating."

"The lack of information is not surprising; with a few exceptions, we have been forbidden to appear on Earth save in particularly dire emergencies," Castiel explained. "I would not be here myself if it weren't for the fact that my friends need help."

"Uh... actually, that's something I was wondering about," Merlin said, looking at the Winchesters curiously. "If you... well, if you hunt magic, why would you... work with a Celestial? I mean, isn't he-?"

"We thought it would be easier to say that we were supernatural hunters rather than explain that we only hunt the bad ones; we've encountered a few witches and supernatural creatures that we've allowed to go free because they weren't actually doing anything wrong," Sam explained, indicating Castiel with a slightly awkward shrug. "Castiel has been a friend of ours for years, ever since he came to advise us on the plans of Lillith, the first and most powerful demon; he often has his own tasks to accomplish, but he's always there when we need him."

"Oh," Merlin said, before he looked at Castiel in sudden confusion.

"Something wrong?" Dean asked, looking at Merlin with a slightly pointed stare.

"Not... wrong, just..." Merlin began, looking uncertainly at the three men standing in front of him before he finally said what was puzzling him as he waved a hand awkwardly at Castiel, as though wanting to avoid personal questions. "He's one of the personal warriors of the Creator... and he looks like that?"

"Ah," Dean said, smiling slightly in understanding as he looked at Castiel. "Yeah, well, long story short-"

"What you perceive is my Vessel," Castiel explained, indicating his borrowed form with a glance down and a slight smile.

"Your 'Vessel'?" Merlin repeated in confusion.

"Castiel's true form would... well, let's just say that the last person who saw what he really looks like was blinded by it," Sam explained, looking apologetically at Castiel for a moment before the angel nodded in acknowledgement of Sam's decision to provide the necessary explanation. "The body he's in is the body of a good and virtuous man who consented to allow Castiel to use his body so that he could aid others on Earth; with his Vessel, Castiel can interact with us and other humans while providing us with his knowledge and powers when danger threatens us in a more subtle manner than he would be able to do so if he was in his natural state."

"Ah," Merlin said, looking at Castiel with a new understanding, before he shrugged awkwardly. "So... why are you telling me this?"

"Because we require your assistance," Castiel replied.

"You need my help?" Merlin said, after a moment's silence as he tried to process what he'd just heard.

"Well, we're actually here to give you our help with something, but once it's done there's something you can help us with," Sam explained. "We've identified the reason for the sudden surge of attacks on Camelot by magical creatures as being the result of a spell that was cast in the throne room-"

"That's what Morgana was doing?" Merlin said despite himself.

"Morgana?" Dean repeated in surprise. "What does she have to do with anything?"

"When Gaius and I defeated her and Morgause in the throne room during the attack, she vanished after she let out some kind of scream that caused the ceiling to collapse around her and Morgause," Merlin explained, looking urgently between the three men as he spoke as though seeking their confirmation of his theory. "I thought that she was just... well, expressing her anger at the fact that we'd just attacked her sister, but..."

"She... it would be accurate to say that she 'rang the bell'," Castiel said solemnly, after briefly glancing over at Sam and Dean to confirm his terminology was correct.

"With that scream?" Sam asked. "That's an actual spell?"

"Calling it a spell would be inaccurate; it would be like considering an infant's cries as having intentional meaning," Castiel explained. "What Morgana did was a primal scream that tapped into the most basic aspects of magic; she was not even consciously aware of it, but she was sending a signal to all magical creatures that Camelot would be vulnerable to attack, even if she could not continue such an assault herself."

"Ah," Merlin said, before he looked at Castiel more directly. "So... what do we do?"