Hello everyone!

Let's start with the tags:

M/M, M/F

Merlin/Arthur, Merlin/Arthur/Mithian, Merlin/Arthur/Lancelot (ONS), Merlin/Arthur/Gwaine (ONS), Merlin/Arthur/Leon (ONS,) background Lancelot/Gwen, background Gwaine/Morgana,

Post Season 5, Time Travel, Fix-It, Alternate Universe Canon, Canon Divergence, Canon typical Violence, BAMF Merlin, BAMF Arthur, Immortal Sir Leon, Magic bonds, Immortality, Idiots in Love, Happy Ending, Angst, Hurt Comfort, Humor, Sexy Times, Threesome

Merlin, Arthur, Lancelot, Morgana, Uther, OFC, OMC, Nimueh, Leon, Gwaine, Gwen, Elyan, Percival, Morgause, Balinor, Mithian, Hunith, Kilgharrah, Aithusa

Next a few infos:

I promise the story won't be abandoned halfway through. It's complete in German and already posted on AO3 and . I will post a new chapter every month.

Thanks to my wonderful beta reader schweet_heart! I couldn't write the story in English without her!

There are a few footnotes in the text. The notes and links to pictures are at the end of each chapter.

I have used those maps: (they are amazing!)
archiveofourown (point) org /works/1037453/chapters/2069264
archiveofourown (point) org /works/1037453/chapters/16736179

I invented two kings for the kingdoms of Kent and Dyfed. King Olaf got the kingdom Deira. Anglia and Tír-Mòr are controlled by the Saxons. My Albion ends in the north with the lands Rheged and Northumbria, that are both ruled by Lords under the banner of King Olaf of Deira, thus making him pretty important.

The Once and Future King

Part1

Prologue

Merlin's only thought as he looks down over the plain of Camlann — still in his disguise as Dragoon the Great — is that he has to find Arthur.

The sun is just setting on the horizon and wafts of mist are slowly creeping over the barren plain. Several small fires have already been lit all over the battlefield, and Merlin only needs one look to determine that Camelot's soldiers are vastly outnumbered by the Saxons fighting for Morgana. After both armies clashed, a bloody massacre had begun, and while fighting man against man, Camelot's military discipline can no longer prevail against the enemy's superiority.

Merlin knows that he has to do something and fast, before it's too late.

Joints stiff from sitting in the saddle for so long, Merlin climbs down from his horse. The mare's coat is clammy with sweat and Merlin pats her neck, grateful to her for bringing him here as fast as she had been able to. After loosening the staff from one side of the saddle, Merlin walks to the edge of the cliff. He can overlook almost the entire battlefield from here, but it's nearly impossible to spot Arthur amidst the chaos of the battle. Following a strange intuition, Merlin closes his eyes and takes a deep breath. Then he sends his magic down onto the plain below and tries concentrating on the thread of destiny that links him to Arthur. His head slowly turns towards the right and when he opens his eyes again, he's looking directly at Arthur, who has been surrounded by several dozen Saxons warriors.

Raising the staff in his hand towards the dark clouds in the sky, Merlin calls upon his magic and a deep and rumbling thunder reverberates over the plain before a flash of lightning strikes the Saxons in front of Arthur. The men are thrown backwards, and a moment later a second lightning bolt strikes and then another, killing the rest of the men that had been about to attack Arthur.

Arthur raises his head, looking for the source of the lightning, and he finds Dragoon on top of the cliff almost instantly. Their eyes meet and Merlin is unable to look away.

"Emrys!"

Merlin whips his head around at the scream that echoes over the plain. He finds Morgana standing on cliff that allows her to watch the battle just as Merlin is doing. He can already feel her drawing on her magic, and he moves his staff in her direction. Another lightning bolt hits the spot where Morgana is standing, and even though she manages to conjure a magical shield in front of her, she gets blown off her feet and thrown backwards. Merlin prepares to attack her again, but all of a sudden Morgana is gone. Sending out his magic, Merlin tries finding her again, but he can't sense her anymore. She's either carrying a magical artifact that's hiding her from his magic, or Morgause taught her a spell that Merlin can't overcome. Whatever it is, Morgana is now aware of Emrys' presence, and she's going to try to kill Arthur before Merlin has a chance to stop her. And that means Merlin has to get down onto the battlefield as fast as possible to keep Arthur safe.

Before Merlin is able to take a single step, however, a deafening roar sounds over the plain, and he tilts his head upwards. Due to the light of the fires and torches from the battlefield, it's hard to see something in the darkening sky, but after a moment Merlin spots Aithusa. The white dragon is flying straight at him with mighty flaps of her wings, and she opens her mouth, preparing to breathe fire at Merlin on Morgana's command. Merlin calls upon the ancient powers of the Dragonlords and after reaching for Aithusa he orders her to fly away and not come back. Aithusa shakes her head, roaring angrily, but she has no choice but to obey the command of a Dragonlord and a moment later she's aborting her attack and flying away.

Merlin's eyes follow her for a brief moment, watching her disappear into the night sky. Then he walks towards the edge of the cliff and starts descending the steep slope. After only a few steps, Merlin realizes that he's never going to make it all the way down to the plain in time to save Arthur in his magically aged body. After the briefest hesitation, Merlin drops the staff and transforms his body back into himself. It doesn't matter anymore that like this everyone is going to find out that he, Merlin, possesses magic, because if he doesn't succeed in saving Arthur, all is lost anyway.

Merlin makes his way down the slope as fast as he can and a couple of times he nearly loses his footing. Finally arriving at the plain, he starts calling more lightning bolts from the sky to cleave a trail through the Saxons towards the spot where he had last seen Arthur. Without the staff, it's harder to control the elements, and Merlin needs more time concentrating before each lightning bolt, but his magic seems to feel how desperate he is and the staff would only have interfered while running downhill.

When Merlin finally sees Arthur amidst the frenzied battle, cold fear grips his heart. Arthur is kneeling on the ground, his gaze unfocused, and he's bleeding from several wounds on his chest where his chain mail has been severed. Morgana is standing over him, her sword raised. Merlin extends his hand and a deafening rumble shakes the ground beneath their feet before a lightning bolt illuminates the setting darkness around them and strikes Morgana with a loud bang.

Once the searingly bright light has vanished and Merlin's eyes have adjusted to the darkness again, he sees Morgana lying motionless, her limbs strangely dislocated, while soft blue lightning still crackles over her body.

"No! You will pay for this, Merlin!"

Upon hearing the angry scream behind him, Merlin spins around, and only his magic reacting for him saves him from being pierced by Mordred's sword. The blade is stopped no more than an arm's length in front of Merlin by an invisible wall and the unexpected collision sends Mordred stumbling backwards. Merlin retreats and extends his hand to call another lightning bolt from the sky, but Mordred has already regained his balance and his eyes flash gold. He extends a hand of his own and throws Merlin backwards with a magical shock wave.

Merlin lands roughly on the hard ground, but while he sees Mordred coming at him with his sword again, something gleaming in the light of the torches catches his eye. It's Excalibur. The sword laying in the dirt only a short distance away. Merlin calls it towards him with a flick of his wrist, before raising it and gritting his teeth as Mordred's sword collides with Excalibur's blade. Merlin mobilizes all his strength and willpower, and the knuckles of his fingers gripping the sword's hilt are turning white, before he finally manages to shove Mordred backwards with a magical push. Using the gained distance between them, Merlin tries getting to his feet again. He succeeds in dodging Mordred's next swing and parries the one after that, but he can feel his strength dwindling. He's no match for Mordred with a sword.

Eventually, Mordred knocks Excalibur's blade to the side and Merlin falls to the ground again. As Mordred raises his sword for the final strike, Merlin realizes that it's over. He's too exhausted to defend himself with his magic and his arms are numb and useless. Mordred is going to kill him and Merlin's only thought is that he has failed. He wasn't strong enough to save Arthur, and the future of Albion along with the future of magic are going to die with him.

The anticipated blow that would slice open Merlin's torso doesn't come, though. Instead, Mordred freezes in midair, his eyes widening. A strangled sound falls from his lips, before the hilt of his sword glides through his fingers. The blade falls to the floor, and it takes Merlin a moment to spot the point of a sword that is jutting from Mordred's chest. The next instant, the sword is drawn backwards and after Mordred collapses, Merlin sees Arthur standing behind the druid boy, Morgana's sword in one hand and the blade red with Mordred's blood.

Merlin stares at Arthur, his mind reeling. Arthur's face is an expressionless mask, his eyes hard, while he's standing a few feet in front of Merlin with the dripping blade in his hand. It takes several long moments for Merlin to become fully aware of the situation. Arthur has just witnessed how Merlin, his manservant and probably his best friend, used magic to kill Morgana and fight against Mordred.

Merlin opens his mouth to say something, anything, but before he can utter a single word, Arthur's nostrils flare, and he grits his teeth, pointing the tip of the blood stained sword right at Merlin.

"Shut up. I don't want to hear a single word out of your mouth."

Arthur's voice was practically a growl, and Merlin swallows heavily. His eyes are fixed on the sword that Arthur is gripping tightly with his right hand.

Merlin has tried imagining the moment Arthur would find out about his magic — it was a miracle that Merlin has been able to keep it a secret for so long — and he had always hoped that Arthur wouldn't be holding a sword when that moment finally arrived. Nevertheless, Merlin has always had faith that Arthur — unlike Uther — would not kill him. The look on Arthur's face, however, makes Merlin realize that he has probably been wrong about that assumption, and he prepares himself for being pierced by the blade of a sword after all.

To his surprise, Arthur doesn't move, and several long moments pass before he speaks again.

"You will leave Camelot, right now. And you will never come back," Arthur finally snarls, barely keeping his rage under control. "I banish you, and if I ever see your face again, I will not hesitate to kill you."

With that, Arthur turns around and walks away over the battlefield. His steps are slow, and he's holding his side with one hand, gripping the blade of Morgana's sword with the other, dragging the bloody tip through the mud behind him.