Original idea by Angst_BuriTTO on AO3 and used with permission for the Merlin WIP Relay.

...

I've got a secret

Can you keep it?

Swear this one you'll save

Better lock it in your pocket,

Take this one to the grave

You know what's said -

Two can keep a secret

If one is dead.

Sixteen years ago

Water dripped somewhere in a corner.

Flickering torches spilled warm light across the stone corridor, illuminating the cold and hostile faces of a man and woman facing each other.

"Take your gold and go. The king will never be told of this or else that…thing in your womb will meet an early end. Camelot does not need a scandal. Do you understand?"

"Please," the woman begged. "He would want to know-"

"Oh, I very much doubt he would with the embarrassment of fathering a child with a nursemaid." The man leaned forward, sneering. "Now, go. Leave before I change my mind and strike you down where you stand, Hunith."

The woman pursed her lips. "You'll regret this."

"I doubt it."

"One day, you will, Lord Agravaine, and I look forward to that day."

Making a dismissive gesture with his hand, the man straightened. "Your threats are meaningless, much like that child. Leave."

Wrapping her cloak about herself, she turned.

"If you tell anyone…"

Her back to him, she stopped.

After a minute of silence, she turned around.

He was gone.

(An hour later, so was she.)

Now

It was a dreadfully boring dinner.

Arthur would have left half an hour ago if not for relations and swearing to his father that he would entertain Lady Amanda and her husband. Now, he was regretting that promise. No matter how many times he shifted in his seat or stifled a yawn, they didn't catch the hint to retire for the evening.

Although Merlin had stopped pouring wine for him half an hour ago, what he had drunk was deluding his head, making everything fuzzy around the edges.

"You have lovely staff, Prince Arthur. Just lovely," Lady Amanda commented nonsensically.

Goodness, he would have given Merlin the day off just for one more goblet.

"Yes," her husband agreed. "Your manservant…"

"What about him?" Arthur snapped, checking his goblet for a fourth time.

Still empty.

Confound it all.

"He looks remarkably like your father at that age! Why, if I didn't know any better, I'd think-"

"Harold!" Lady Amanda scolded.

"Oh, shush, my love, I was only rambling. It's simply a coincidence." He sent a slightly worried look at Arthur. "Pardon me, my lord."

"Of course."

"Weren't we just saying that we need to hire more staff, Harold?"

The two of them started going off about how difficult it was to find decent men and women (amen to that, Arthur thought), and Arthur slumped down further in his seat.

Only two more hours to go, and Merlin wasn't even going to let him get drunk.

It was going to be a long evening.

The next morning, Arthur held his head in his hands and moaned.

"I told you not to drink that much," Merlin cheerfully gloated.

"I wasn't even drunk. And I'm not hungover." His head just felt…stuffy, unusable, and pained.

He was supposed to be writing a speech for the next public dance to be held at the castle, but he couldn't concentrate on stringing words together. He'd probably have Merlin do it for him later after he finished making up Arthur's bed.

And, on top of that, staring at Merlin, he couldn't get Lord Harold's words out of his head no matter how hard he tried.

"He looks remarkably like your father at that age! Why, if I didn't know any better, I'd think-"

It was probably a trick of the light. An effect of the previous evening's wine. Arthur's desire to think of anything else but the blasted speech he couldn't write.

But he could see it.

Now that the idea had been put into his head, he couldn't not see it as he looked at his manservant.

Merlin looked like his father.

His nose was definitely a copy of Uther's, and his hair was as dark as Uther's had been when the king was a child. At least, as far as Arthur could tell from old portraits. It was also slightly curly.

Merlin's cheekbones, of course, were more prominent than Uther's, but if they were lower and he fattened up a bit and his jaw were to be a little wider…

His face would be almost identical to Uther's.

And his eyes.

Every time Merlin sent a curious glance at Arthur, he saw his father's eyes looking back at him.

Arthur had no proof besides an old man's words and the resemblances he saw.

But Arthur knew his father.

If Uther had another child, he would have claimed it in some way. Perhaps if it were a girl, he would have made her a ward and brought her to the castle to grow up with Morgana and Arthur. Although Uther failed sometimes as a father, he couldn't stand letting his own blood go unclaimed, especially after the death of Ygraine. Every drop of blood with Pendragon pride was precious, and he held as tightly onto it as a dragon protected its hoard.

So if Merlin was Uther's child, Arthur's brother, an heir to the throne…Uther didn't know.

But it was impossible. Arthur couldn't have a brother, and if he did, it surely couldn't have been Merlin.

Right?

"Merlin, how old are you?"

In the middle of folding a shirt, Merlin paused and looked up. "What?"

"How old are you?"

"What's that got to do with your speech?"

"Nothing. I'm just curious."

"Are you feeling ill?"

"No! I just wanted to know how old you are!"

Through narrowed eyes, Merlin looked him up and down. "Fifteen," he finally answered, resuming folding the shirt and flattening it.

"Fifteen? You can't be."

"You think I'd lie about that?"

No, Merlin wouldn't. If anything, he'd make himself older. Arthur just hadn't realized how young Merlin was. At fifteen, Arthur himself had only started his knight training, and fifteen years ago, he had been around six years of age.

He tried to think of anyone his father might have been…familiar with during that time. There was his mother before she died, of course, but she didn't help fit the pieces of the puzzle together, and he didn't think Uther would have been friendly with any visiting noblewoman.

He couldn't think of anyone except-

-his nursemaid.

Her name started with an H - Helen? Hunith? Yes, Hunith. She'd disappeared without so much as a goodbye when Arthur had been approximately six years old, and he had been devastated. He remembered crying for weeks, and his father had been exceptionally furious.

At the time, he thought it was because of his behavior, but what if there were another reason?

What if Merlin was the reason?

What if Hunith had left Camelot because she was pregnant with Uther's child? Why would she have?

He was jumping to a lot of conclusions.

"Merlin."

"What is it now, Arthur? Honestly, if you keep bugging me, I'm never going to get anything done, and then you're going to whine-"

"What's your mother's name?"

"My mother's name? What, want to include that in your speech, too?" Merlin threw up his hands. "How about my whole family history? I'm sure everyone would like to hear about that."

"Just answer the blasted question."

"Hunith." Merlin threw the neatly folded shirts into the bottom of the wardrobe.

"Hunith?"

"That's what I said," Merlin snapped. "Why?"

Because I might have stumbled across one of the greatest secrets of my life, Merlin, and you're smack dab in the middle of it.

"I was just wondering. It's of no importance to me, of course. Just curiosity."

"Right. Well, unless you're still curious about the name of my cousin thrice removed, I'm going to go muck the stables, sire."

At the honorific, Arthur flinched. If Merlin really were his brother, Arthur had been wrongfully treating him like a servant all this time.

"No, go ahead."

"Good."

Merlin made for the door.

"Merlin?"

Hand on the knob, Merlin paused.

"You're sure it's Hunith?"

"Positive," Merlin told him flatly. "I'm pretty sure I would know my own mother's name."

Before Arthur could say anything else, he left the room, slamming the door behind him.

Not really seeing anything, Arthur stared at the blank page and the dripping quill in front of him.

If Merlin really were Uther's son…

But Arthur didn't know for sure. He would have to make certain of it, and the only way to do that was to speak to Uther himself.

He only hoped the reaction would be positive. Even if Uther valued blood, he might not value this blood.

Arthur swallowed a piece of chicken.

It went down his throat like a burnt log.

He wasn't sure how to bring the matter up.

Hey, Father, have any spare children running around?

When Arthur sighed for the third time, Uther looked up and raised an eyebrow.

Now was as good a time as any. "I was wondering if I might ask you about a matter," Arthur ventured, setting his fork down.

"Yes?"

"Do you remember my old nanny, Hunith?"

In the middle of lifting his goblet of wine to his lips, Uther hesitated. Setting it down slowly, he narrowed his eyes. "Why?"

Arthur took his own sip of wine. He was going to need it. "Curiosity. I recently discovered that my manservant's mother's name is also Hunith. I did not think it was that common."

"It isn't," Uther said through clenched teeth. "But I hardly see how that concerns me."

"She's been gone for…sixteen years?" Arthur sloshed his wine around a little and took another sip. "Same age as my manservant Merlin. Funny coincidence, don't you think?"

Uther didn't answer.

Arthur was hitting a nerve, but now that he had started tearing the bandage off, he couldn't stop. He had to know the extent of this. "I wonder why she left. Do you think she could have been with child at the time?"

"Arthur, what, exactly, are you attempting to imply?"

"Nothing. I was merely thinking aloud."

Uther's face was pinched and angry. "I think I would know if I had another child, Arthur, and it certainly isn't that idiodic manservant of yours."

"Are you sure you would know? Hunith left without saying goodbye to me."

"You were six years old, Arthur."

"Still," Arthur insisted.

"What you're implying-" Uther growled before reigning himself in.

But Arthur wanted him to go on. He needed to know what had happened sixteen years ago.

Too many coincidences were stacking up.

His father was merely getting angry at the notion - not outright denying the possibility even though the opportunity had been given to him. Either Arthur's assumptions were completely wrong or he was embarrassed that he didn't know or…

Or he saw the connection himself.

It was enough for Arthur to take and run with.

"Excuse me, Father. I seem to have let my curiosity get the best of me." Arthur took another sip of his wine.

Meanwhile, as he clenched and unclenched a fist, Uther seemed to have forgotten the food even existed.

When Arthur left, Uther was staring into the fire of the hall's hearth, a fist under his chin and a thundercloud on his brow.

Obviously, Uther did not know why Hunith left Camelot so many years ago.

And, from what he had seen, Arthur doubted that he would have been the cause, so now Arthur was faced with a mystery.

Why had Hunith gone to Ealdor?

It would have been easiest if he could ask her outright, but she wasn't around, and Merin would probably get nosy and concerned if Arthur started asking about his mother again.

Goodness.

Merlin.

Arthur didn't know what to do with him.

Lying in bed in the dark, he was already dreading waking up in the morning to his manservant's cheery voice with the knowledge that he carried.

They were brothers.

Merlin was his brother.

From another mother, of course, (half, then, his brain supplied), but still his brother.

When they had first met, Arthur would have been appalled at the idea.

But now?

For a moment, Arthur squeezed his eyes shut. He couldn't think about that right now. His priority was digging up the truth.

If Uther was Merlin's father, Arthur doubted that either he or Hunith would have wanted a separation.

A second prince - illegitimate or not - was a valuable asset. If, by some chance, Arthur died, Hunith and Uther could marry, and their child would be able to claim the throne in the instance that Uther died as well.

A "spare heir," if one willed.

It would keep the country from erupting into civil war even though the chances of such an instance were extremely low.

(At least, Arthur liked to think that they were.)

Who would have both known about a second child's conception and wanted it quietly gotten rid of at the same time?

Turning over on his side, Arthur tried to think.

He did not remember as much as he would have liked to from when he was six years old.

There was Hunith, of course, and him running around, causing mischief unbefit for a prince.

At that point, he also remembered his uncle Agravaine residing in the castle. Often, his uncle had been a target of that mischief, and Arthur (fondly) recalled getting on his nerves plenty of times. If his memory was serving him right, Agravaine walked around like an oily snake.

He sat up in bed.

Lord Agravaine.

At six years of age, Arthur didn't like him, and his opinion of him now was only marginally improved.

His eyes had always carried a calculating look.

A distinct possibility existed that he could have known about something or been involved somehow.

Gaius would know. He had been the court physician back then and could probably still remember a bit of the gossip that had flown around.

But it was the middle of the night.

No matter how tempting it was, he couldn't wake the older man up at this hour.

He flopped back down into his pillows.

Now that the idea was in his head, he wasn't going to catch a wink of sleep.

It was going to be a long evening.

Arthur ambushed the Gaius as the court physician made his customary rounds throughout the castle delivering potions and other things to the ailing.

"I need to speak with you. Is Merlin around?"

Gaius sent a confused look from the crevice out of which Arthur had just sprung to the prince himself. "No, sire. In fact, Merlin has been looking for you all morning. Are you feeling ill?"

Arthur ignored the question. "Listen, I need you to think for a moment. Sixteen years ago. Do you happen to remember anyone who might have carried any ill will towards my father?"

Gaius raised an eyebrow. "Aside from every sorcerer?"

Arthur dismissed the notion. A sorcerer would have killed Hunith and then moved on to the rest of them. "Anyone in the court. Would Lord Agravaine know?"

Gaius's eyebrow inched higher. "Are you asking me to discuss court gossip from over a decade ago?"

"No. Just anything you might have heard." Arthur would take any scrap of information he could find.

For a minute, Gaius thought before speaking. "If my mind is serving me correctly, your father and Lord Agravaine were in the middle of a particularly nasty spat that lasted for a while sixteen years ago. May I inquire as to what brought on this…line of thought, sire?"

"Curiosity. I heard a rumor."

So his uncle and his father hadn't been getting along.

Was it too much of a jump to assume that perhaps Agravaine had heard of Hunith's pregnancy before Uther did and told her to leave?

No, that couldn't be right. As far as Arthur could tell, Uther and Agravaine were currently on good terms, and Uther hadn't known about Merlin's possible heritage until Arthur mentioned it.

Of course, Agravaine had not visited in a long while.

It was possible that Agravaine had scared Hunith off out of retaliation for some slight.

Arthur needed more than his suspicions and old gossip from Gaius, however.

He was so close to the truth that he was getting a headache.

"Are you all right, sire? Would you like me to fetch you a tincture?"

"No," Arthur snapped. "I'm positively fine." He just needed to connect Uther, Hunith, Agravaine, and Merlin.

"If you'll pardon me, then, sire, I have other patients to attend to."

Stepping to the side, Arthur let him pass.

Blast it.

Despite that tidbit of information, he felt like he'd gotten nowhere, and he needed this solved before it drove him insane.

After all, he could only avoid Merlin for so long. His manservant probably knew something was up, and Arthur couldn't think of a blasted explanation to it all.

Turns out my father and your mother might have been a thing back in the day, and by the way, we're probably half-siblings?

Merlin would laugh in his face.

On top of that, would Merlin even want to be related to him? Arthur liked to think that they were somewhat…friends, but Merlin was…Merlin.

Oh, blast it, he didn't know. He'd spent half the night thinking about it and now he was off on it again.

As though he'd ever stopped.

He needed to keep his mind and his hands busy with something else.

Training.

That's what he would do.

Nothing like swinging a sword around to clear the mind.

Because Merlin was nowhere to be found when he entered his chambers (thank goodness), he was left to his own devices to suit up for training.

It did not go well.

"Did you know Merlin was looking for you?" Percival asked as he swung his blade at Arthur's neck.

Arthur danced out of the way.

"He said you were up before he was."

"I had things to do."

"Really?"

Arthur answered the question with a thrust.

Percival parried it. "Did something happen?"

"No."

"Is that why you're putting dents in everyone's armor?"

Arthur took advantage of Percival's distraction to feint left, cross right, and snag the hilt of Percival's sword.

With a swear, Percival dropped the weapon.

Panting, Arthur wiped his forehead and lifted his eyes. "Who's next?" He raked the sidelines, looking for his next victim.

There stood Merlin, his customary red handkerchief around his neck and his hands on his hips.

Well, fie.

"All right, out with it."

"Out with what?"

"Whatever's been bugging you. Honestly, who put this on you? A blind man?" Merlin groused as he worked to get Arthur's training gear off him. "I know something's wrong. You woke up early, skipped breakfast, and now you've been avoiding me all day. You've been acting weird ever since you asked about my mother."

Arthur opened his mouth. Closed it.

This was exactly why he was avoiding Merlin.

He still hadn't come up with a way to convey his suspicions properly.

"On top of that," Merlin went on as he tossed Arthur's equipment into the corner to deal with later, "Gaius told me you questioned him about my mother and several other people from sixteen years ago."

Arthur winced.

He should have asked Gaius to keep quiet about it, but that the court physician would run and tell Merlin hadn't crossed his mind.

"That's none of your business," Arthur said, rolling his shoulders backwards to attempt to fix the knot in his shoulder and the weird position that his shirt was in.

Merlin stepped back and crossed his arms. "It's my business when my mother is involved." Steel underlined his words, and there was a flint look to his eyes.

"Your mother isn't in any trouble or danger," Arthur promised him.

At least, he didn't think she was. Unless Uther tried something, but he doubted his father could reach into Ealdor like that or that he would.

He hoped.

Although assassins were still in style.

"How come I don't feel assured by that? What's going on?"

"Nothing." He pressed his mouth into a thin line, hoping Merlin would catch the hint that he didn't want to talk about it.

Huffing, Merlin rolled his eyes. "Arthur, whatever it is, it's obviously bothering you, and if you'll just tell me what it is, I can help."

Merlin was always helping him. He was like the plague, always hovering by Arthur's elbow, following him wherever he went even if it meant skulking around in the woods in the middle of the night.

"You can't help me with this."

Merlin's expression said try me.

And as much as Arthur feared Merlin's reaction, a small part of him wanted to know Merlin's thoughts. On a regular basis, he expressed disdain for anyone with a hefty rank and puffy pretenses and poked fun at Arthur over the littlest things. Would he be disgusted to know he was related to Arthur?

What if he told Merlin and Merlin completely rejected the bond that was supposed to exist between them?

Everything would be ruined.

Nothing between them would ever be the same again.

The words would be irrevocable, and there would be no going back.

A slight shudder ran down Arthur's spine.

He couldn't do it.

He would never admit it to Merlin, but he just could not do it.

"You cannot help me with this," he repeated icily. "Now shut up and do whatever it is that you're supposed to be doing."

For a second, a wounded, irritated, and confused look flashed across Merlin's face, but he rolled his eyes. "Yeah, sure, Arthur."

"I mean it, Merlin."

Why couldn't Merlin just leave well enough alone?

"If you-"

Merlin raised his hands. "Fine. I won't say another word about it. Promise."

Oh. Well. That was rather considerate of him.

It would be absolutely best if Merlin forgot about the whole thing.

Merlin did not forget about the whole thing.

"Merlin, stop whistling."

"If you don't stop singing that hideous tune-"

"You'd better drop that again, Merlin - I don't think you woke the dead in Deorham."

"For goodness' sake, would you stop staring at me?"

Arthur pounded his fist on the table. "Confound it, Merlin, I can't think!"

"Sorry," Merlin tossed back without any conviction.

"Can't you go…exercise my hunting dogs?" Yes, that was perfect. Outside of the castle.

"Sure," Merlin agreed.

Suspiciously, Arthur watched as Merlin tidied up one last thing and left.

At last, peace - outwardly, at least - reigned. Arthur propped his feet up on a spare chair and leaned back, exhaling. Maybe now he could think about the situation and determine the best course of action.

From the courtyard, a hunting dog brayed.

A second later, the rest of them started yipping, yowling, and yelping.

Arthur dropped his feet from the chair and put his head in his hands.

The noise did not die down.

"Ah, Arthur, there you are!"

Gwaine slung an arm over Arthur's shoulder.

Arthur side-eyed him.

"Just the person I wanted to see. I'm about to head to the tavern. Want to join me, princess, or are you too busy counting your petticoats?"

"I have a headache, sorry. Maybe some other time."

And by some other time, he meant never, because drinking with Gwaine usually meant footing the bill as well.

"All the more reason." Gwaine started pushing him in the direction of the outer town.

"No, really, Gwaine, I mean it. I'm not going drinking with you."

Gwaine's ears were great.

Wait, no.

Arthur had to think about that one.

Gwaine's ideas were great.

Yes, that was what he meant.

Gwaine's ideas were wonderful.

(His ears were a little ugly, though, come to think of it.)

Arthur didn't remember the last time he'd felt so empty and light, and he wondered why he hadn't gone with Gwaine to the tavern.

Fie, he was going to go to the tavern every night from now on!

Snorting, he went to down the rest of his ale and ended up slowshing the rest of it over the front of his shirt.

For a second, he frowned.

How sad.

Ah, it didn't matter. Merlin would take care of it, anyway.

"Arthur! How plastered are you?"

Speaking of the devil.

"Merlin," he slurred. "What have you been? You're always at the tavern."

"Yeah, I know." Merlin yanked the mug out of his hands.

For a few seconds, Arthur tried to figure out where it had gone while Merlin finished off the drink.

When he finally discovered it, he frowned. "You're the worst manservant ever."

"Yeah, I know." After dropping the empty tankard on the counter, Merlin hauled him to his feet, and they were outside the tavern in the dark streets before Arthur knew what was happening or could protest.

Arthur frowned. That wasn't fair. He wanted to keep drinking, but his mug was nowhere to be found even though he groped around in the dark for it.

"You're the worst manservant ever," he repeated as Merlin tried to drag him in the right direction. "I'd fire you if you weren't my brother."

Merlin snorted. "You really are plastered."

That wasn't fair. He wasn't drunk. He was as sober as…he was as sober as…a rock.

"'S true," he insisted. "You're my…"

Oh, blast it, he'd forgotten the word.

"Brother!" he exclaimed when he finally remembered it. "My father and…Hunith…"

Merlin froze, and without his support, Arthur listed to the side.

Now he was on the ground.

He could not possibly remember how he'd gotten there.

The world rattled around. At first, he thought he was going to throw up, but then he realized that Merlin was shaking him.

"What about your father and my mother?"

"Your father," Arthur corrected. "Our father." At the idea, he laughed.

"This isn't funny or some sort of joke."

Well, Arthur was insulted. He wasn't joking. In fact, it was rather nice to get this weight off himself because he felt like he was floating now. "I'm not," he said. "I asked him. Wouldn't deny it. Turned all…red in the face like he does."

Amid Arthur's drunken stupor, Merlin's face came into focus, white as a sheet.

"S'rry," Arthur said because it felt like he needed to say something but couldn't figure out what was wrong.

Crouching next to him, Merlin tried to wrap an arm around his side to haul him up, but Arthur was far heavier than the scrawny boy.

Since Merin was already halfway there, Arthur did the logical thing and wrapped his arms around him.

Merlin froze.

"I'm glad you're my brother, Merlin."

Even though his cheek was rather uncomfortably mashed into Merlin's bony shoulder, he sighed happily.

There were voices, one carefree, the other concerned.

"Can you help me get him back to the castle, Gwaine? Gwaine? No, I'm not going into the tavern! I just came out, and I need to go-"

Arthur heard his own snoring and wondered when he had started doing that.

Arthur woke up feeling disoriented and sick.

He had just enough time to find the chamber pot under the bed before throwing up, and he groaned as a headache pounded its way through his temples.

Peculiarly, his window curtains were open, and the piercing sun was hitting his eyes.

Where was Merlin?

In fragmented bits and pieces, the details of the previous evening came back to him.

Drinking enough to drown a whale.

Stumbling everywhere, the world upside down.

Telling Merlin things.

Oh, goodness, what had he done?

Merlin was nowhere to be seen. At that hour, he should have been there, opening the blinds and sinking like a broken canary.

After throwing the bed covers off himself, Arthur scrambled to find his boots and a shirt.

Later, he wouldn't remember running through the castle, but he would be able to recall pounding on Gaius's doors and the shaking of the wood underneath his fist.

It cracked open, and the physician appeared. "My lord?"

Without waiting for an invitation, he pushed into the room. "Where's Merlin?"

"Merlin?"

"Yes!" Arthur snapped, whirling around after a brief search of the room yielded no trace of him. "Where is he? Did he return here last night? Did you see him leave?"

Gaius's face told him everything.

Merlin was gone.

"You told me it was my destiny to protect him!"