The Lady Morgana was, quite frankly, terrifying.

Surely, Gaius thought distantly, he should be struck by some remnant of his old affection and respect for her, or some memory of her as a young girl scared to sobbing by one of the nightmares that plagued her. Something should surely intercede to lessen the impact of this scene: Morgana, tall, cloaked in rich green and full of dark sorcery, standing in the throne room, returned to Camelot to humble the great city and exact her revenge against her former guardian.

But no memory would dull this moment; this Morgana was completely alien to the person she had been before. There was no physical change to pin it on; she still had the same imperious pale forehead, the same flashing eyes. She had always had an intimidating beauty that had filled the onlooker with awe and attraction in equal measure. But now, without the kindness that had once softened her, there was nothing to temper the fear she inspired. Hers was now a chilly, terrible beauty, which would never warm the beholder as true beauty did.

There was her magic too, piercing the room with an icy chill that cut to your bones and had nothing to do with temperature. That must have been what the inhabitants of the villages at the borders of the kingdom had felt, without recognising the magic for what it was, when they sent messengers flying to Camelot to tell of the cloaked figure stalking towards the royal city, leaving peasants shivering in its wake, seized by an uneasy, uncertain dread.

The messengers had done very little good. True, it had allowed them to organise a party of knights to meet the stranger outside the gates. But that had merely meant more of Camelot's men dying as Morgana cut through them ruthlessly, with magic, with her sword. It had seemed effortless, accomplished with a grace in keeping with her deathly beauty. And everything about it inspiring the utmost terror and despair in those watching as they saw their best and bravest cast aside like so many incidental distractions.

Gaius didn't know at what point the cloaked stranger had been known to be Morgana, but there had been strikingly little surprise in any quarter. They had known she would return one day. They had known that Morgana did nothing by halves and nothing imperfectly. And strange and alien as this hostile Morgana was, some things hadn't changed. They had known her quick anger and her unbending determination. In short, though none of them had spoken of her since her exile, somewhere in their souls they had known this would happen.

She stood now at the entrance to the throne room, and Gaius's eyes kept flicking from her uptilted jaw and pursed lips, to the spot a few feet behind her where Arthur lay dreadfully unmoving on the floor. He had barred her way at the entrance, reminded her that the terms of her exile allowed for no pardons and no return. In reply she had struck him down with a terrifying burst of energy that confirmed all of Gaius' fears of the power she had gained among the druids, and dashed any remaining hope he might still have had.

"He's not dead," she declared in ringing tones that were awfully familiar and yet strangely distant, almost unreal. "But anyone else to stand against me soon will be. I am here to take from Uther the life he has taken from so many magic users, and the throne he claimed in spilling their blood." Her eyes surveyed the room, taking in the court stilled and almost spellbound by her imperious tones and calculated violence.

"And was I wrong, Morgana?" Uther growled, and Gaius, knowing the king as he did, could tell that the anger vibrating in his gruff voice was merely transmuted fear and grief. Magic, the thing he most feared and least understood, had as far as Uther was concerned stolen his daughter, felled his son, and invaded his court. The man was shaken to the core but could never show weakness even against an enemy he could never hope to best. "Look what magic has done to you: it has made you a traitor and turned you against Camelot! I was right to fear that magic would destroy this city!"

"You made me a traitor, and you have destroyed this city," Morgana spat, with a voice of venom and eyes of cold fire. "I am of your making, my lord, and you cannot disown me in that respect, even if you no longer regard me as your daughter." She smiled, lips parting in malice. "Was it not you who taught me that might rules without mercy and brooks no compromise? Now the might is mine, Uther, and you shall submit to my power before you meet your death."

And Gaius wondered if Uther, blind as he was to so many things, might nonetheless glimpse the truth in Morgana's words: she was of his making, not just because he had been responsible for her upbringing, not just because he was responsible for her exile and persecution, but because she truly was the heir to his rule. If Arthur at times seemed to embody all that was once good in Uther's reign, the justice and the fierce desire to protect his people and bring peace to the country, then this Morgana held a terrible refinement and exaggeration of everything that had since soured and rotted at the heart of Camelot; she had inherited a blindness to true justice, a blinkered belief in her own rectitude and a cruelly unyielding wielding of power. Gaius hoped that Uther couldn't see it; mistaken as his friend was at times, Gaius could not wish on anyone the knowledge that they had created a monster.

Uther, of course, could not be held entirely to blame for the woman Morgana had become. The druids would have played their part, after Morgana sought them out, yearning to explore her magical powers and take her revenge against the king who had wronged and exiled them all. Their influence would not have been limited to encouraging her treasonous ambitions; Gaius well recalled the tinctures and potions the druids had been known to use to enhance their powers. He was sure that, knowing Morgana's power, they would have given her their most potent mixtures, and that she, in all her boldness and determination, would have taken them, in spite or in ignorance of the various secondary effects they often had on the user; paranoia and an ever hazier connection with reality would have had their own role in widening the abyss between this Morgana and the lady she had once been.

Uther's voice had been silenced by a spell now, Gaius saw, and the king glared impotently and yet defiantly at the sorceress as she took a step towards him. She glanced up as the people surrounding her stirred uneasily, and smiled to see their fear of her.

"Will none of you step forward to defend your king?" she demanded. Gaius followed her gaze as her eyes swept cruelly over the stilled knights, some gazing helplessly at their imperilled king, others sliding fearful glances at their fallen champion: if Arthur could not best her, which of them could? Gaius knew that he had seen these same knights leap to Camelot's defence in the most suicidal of circumstances in times past, but Morgana knew how to make an impression: she had crushed their hope and ensnared them with terror, and none of them would cross her now.

Gaius's eyes slid hopelessly to Merlin, quiet beside him up until now. Blue eyes he knew so well met his, and Merlin nodded, a small thing, barely perceptible, but all that needed to be communicated between them. Gaius was flooded with relief and dread, and he was frozen to the spot as he watched Merlin step forward, smooth and deliberate as he never was usually, and quietly tell the sorceress, "I will."

Gaius was seized by the protective instinct that had gripped him as long as he had known the boy, torn between the imperative to stay put and unnoticed and the desire to shield Merlin, to tell Morgana the boy was talking nonsense and to keep him safe and unremarked beside him... But that was never to be Merlin's path, to be unremarked, never really had been despite Gaius's best efforts, and this time it was not cowardice that stilled Gaius's voice and prevented him coming to a sorcerer's defence. This was Merlin's time, the moment he had been waiting for without knowing it, and to intervene now would be to throw off course a destiny greater than all of them. Merlin's lot had always been to place himself between Camelot and the threats to her peace, and Gaius could not expect him to do any less now.

"Merlin," Morgana said, and her face stilled, no hint of dreadful laughter in her voice now that she was faced with something she had not planned for and did not view as a threat. "Get out of the way. You cannot hope to stop me. This is no time for foolish bravery; I make no idle threats, and even if I once knew you, do not think I will not kill you if you oppose me."

"Then you will be no better than Uther," Merlin said intently. "And you are better than that, Morgana. This isn't the only way- you can still turn back." It was the wrong thing to say and Morgana bristled. And Gaius could not speak up, could not intervene, and who else would? Arthur had already fallen; Gwen, never wanting to be noticed at the best of times, was positively trembling with fear and indecision, faced with her once beloved mistress now become something so monstrous. If there was no-one to defend the king but Merlin, then there was certainly no-one to come to the aid of a lowly servant.

"You think you can persuade me to turn back, Merlin, you believe you have such power?" Morgana spat the words contemptuously. "Tell me, if I am so much better than Uther, why do you not welcome me? You surely can't believe his reign is just."

"You would not be anything more than a tyrant either, if you take the throne by force. Turn away from this, Morgana, please. This will not help anyone."

"It will help the users of magic who have been oppressed by Uther, all of the people who could benefit from the magical arts to which they have not had access. Change cannot be achieved unless the will for change is accompanied by the power to make it happen and no king has obtained his throne by any means other than force."

"But not by magic," Merlin said more forcefully, beginning to lose his calm in his desperation to avoid a confrontation with his former friend. "Whatever uses magic may have, it is not meant to rule. Men should not be ruled by that which is not of men, and no good can come of your reign if it begins this way."

"Enough," Morgana cried in anger. "I have left you enough time for your sentimentality, Merlin. I am here to take the throne, and since you have neither sword nor magic with which to stop me, I suggest you stand aside and let me."

"And didn't your dreams... didn't you see?" Merlin asked, taken aback, and Gaius realised that the boy did not realise that Morgana might not know of Merlin's powers. The seer's art had ever been fallible, particularly when their own fate was involved. He watched Merlin's head rise with renewed determination. "Then... If you attack, Morgana, I will fight. And Gwen..." he sought his friend out in the watching crowd. "Whatever happens... I'm sorry. And tell Arthur... tell him that too, just tell him I'm sorry." He turned his gaze back to his opponent. "I will not let you harm the king, Morgana. Turn back, or remove me by force.

"If you so wish to die, then..." Morgana paused, anger still in her voice and expression, and then her eyes narrowed like a hawk seeing its prey. Words of the old language pierced the air, drawing behind them a lance of fire which arced high into the echoing ceilings of the throne room, before crashing down onto Merlin, who seemed to cut a suddenly slight figure in the face of such an onslaught, disappearing under the waves of fire that crashed over him. But as the dancing flames receded, he stood unbent, unharmed, with one arm outstretched and the last remnants of that fire dancing across his palm before dying. A gasp ran around the room, but Merlin and Morgana never averted their gazes, as if suddenly they were the only ones in the room.

"Now you know what I am, Morgana," Merlin called defiantly. "Know that whatever your claim to represent users of magic, I do not believe your path to be either the only or the best way to return magic to Camelot. Know that I will resist you with all my power. Know that and decide again: will you turn back?"

"You are a coward if you have hidden your magic this long, Merlin," Morgana glared. "You're a traitor to all sorcerers. And you think you can defeat me?" She raised a hand and began to speak, but all Gaius saw was a flashing movement in the air between the two spellcasters before words of the old tongue began to pour from Merlin's lips too, countering Morgana's spells. Gaius couldn't follow the intricacies of their combat, simply heard the chiming chords of their spells and saw the air flickering between them, acted upon by forces and energies powerful but unseen. And he was awed at the incredible force being expended in that room and wondered if anyone else present understood how truly breathtaking the two sorcerers' power was.

And then a tension that Gaius hadn't even noticed building dissipated, a resounding silence filled the room and Morgana was breathing hard and her eyes were wide, looking for all the world as if she had been slapped. Merlin bit his lip and watched her.

"Will you turn back?" he asked simply. "Please, Morgana." But the hurt on Morgana's delicate face coalesced into anger.

"I will not yield to you, nor any other," she spat, and her hands flew up, her cloak billowed out in a wind no-one else felt, and then Merlin's hand made a slight movement, a couple of words of the old tongue fell from his lips, and the terrible energy around Morgana was dispelled. She caught her hands up to her chest and dropped to one knee, and her breathing caught for a moment as if the air had been stolen from her lungs which, Gaius surmised, it very likely had been. Stealing the words of a sorcerer as they spellcast was a complicated and rarely-employed spell, but Gaius happened to know it appeared in the later pages of the book he had given a young boy who had just arrived in Camelot.

"I will not yield," Morgana bit out, the burning fury in her eyes still fixed on Merlin. "Never. You cannot win this fight if you are not willing to finish it, Merlin. Kill me now, or know that I will not rest until I see Camelot humbled before me." Her voice trembled and rang with defiance and self-belief.

But as Gaius began to turn towards Merlin, not sure what intent he would see on the boy's face, two vials tumbled through the air between the two magical combatants, shattering shrilly on the stone floor and filling the room with a dense, roiling smoke. A series of disorientating shouts cut through the air, but Gaius picked out Morgana's admonition to her rescuers: "Mordred, no!"

"It's the druids!" someone shouted, but in moments the smoke was clearing and soon had disappeared, and Morgana and whoever had carried her out of danger were gone with it.

There was just Merlin, stood in the centre of the room, hands hanging uselessly by his sides as if he no longer knew what to do with them. But his gaze glittered with a self-assurance Gaius had not often known him possess before, and the eyes of everyone in the court were transfixed on him, and Gaius realised with a start that he could not have felt more proud.