Merlin closed his eyes, feeling the walls spin around him. He had failed.

"But we will hold you to your promises," the Disir continued with one voice.

"What does that mean?" Merlin cried.

"Fulfill the promises you made us, Arthur Pendragon," the Disir chanted and then spoke no more.

Stunned, Arthur and Merlin walked out of the cave into blinding sunlight. They rode back to Camelot silent and weary.

"You didn't have to speak for me, Merlin."

"I had to! I believe in you!" Merlin replied, his words coming out more like an accusation rather than acclaim. Arthur watched him thoughtfully. Merlin swiped angrily at the tears on his cheeks and refused to look at Arthur.

"Have I made a mistake, Merlin?"

Merlin gave him an inscrutable look. He shook his head. "I don't, Arthur. I don't know."

They reached the castle in the warm, golden light of the evening. As their horses' hoof beats sounded in the courtyard, Mordred came running down the steps to greet his king and Merlin watched him and swallowed his own failure once more. He had not changed the past, nor the future. Mordred lived to serve Arthur's doom. The Disir's judgment stood.

As Arthur and Mordred embraced, Gwaine came running towards them. He was dusty and dirty as if just returned from a journey.

"Merlin," he shouted, getting Arthur and Mordred's attention. "I have found the tower." He looked between Merlin and Arthur, his eyebrows drawn together and his mouth a tight line. "I found it and it was hell itself."

...

On the pallet where Mordred had lain in Gaius' rooms, lay sleeping a young woman. Arthur and Merlin and Gwaine and Guinevere stood around her. She was pale, her long hair, the colour of dark amber was roughly braided to one side. Gaius pressed a finger to his lips.

"She needs to rest, Sire."

"The man who ruled the tower is dead," Gwaine had told them. "I killed him myself after seeing his 'collection'." Gwaine shuddered and Gwen drew close to Arthur. "Percival and I released all the slaves. But in the caves beneath the tower, we found bodies that had been tortured, mutilated beyond recognition. There was one still alive who begged for death." Gwaine paused, a haunted look in his eyes.

"And the girl?" Guinevere asked.

"Her name is Bri. She hadn't been there long," Gwaine said, shaking his head. "A few days at most. He hadn't done her any harm yet, but if we'd been a few days later..." he trailed off and shuddered again, his face fierce. "If Merlin hadn't told me about it..."

Arthur frowned at Merlin.

"How did you know about this tower?"

"An old woman, uh, a traveler told me."

"What matters is that the tower is destroyed and she's safe," Gwen said, laying her hand on Merlin's forearm. "Had she no family to go back to?" she asked Gwaine.

He shook his head. "Her captor had killed her family, and razed her keep to the ground. She had nowhere to go."

"I will let you know when she awakes, Sire," Gaius told them and gently ushered them out of the room. He turned to find Merlin still sanding looking down at the girl.

"I can't believe it's her, Gaius," Merlin whispered. "Night and day. She was so much younger than I ever imagined."

Gaius frowned. "What are you talking about, Merlin."

Merlin looked up and met his gaze.

"Oh, Gaius! There's so much I need to tell you."

"Can it wait until we've had our dinner?"

Merlin smiled, but his eyes were sad.

"There's not much hurry. Not any longer."

The fire danced in the grate late into the night, making shadows on the walls. Merlin told Gaius the long story of his future and past. Gaius listened wide eyed, without commentary, and patted his hand when the telling brought tears again to Merlin's eyes.

"So Mordred did turn on Arthur," Gaius reflected. "I wouldn't have believed it."

"He had reason to, Gaius," Merlin replied bitterly.

"You've traveled a weary road, Merlin. It can't have been easy."

"I had one chance, Gaius, one chance to fix it all, and I messed it up. I will not get another." Merlin put his head down into his hands.

"Merlin, how many times have I told you that there are many possible futures and no one can know for sure what they each hold? One thing I know for sure, the path you are on now, will be different than the one you've walked already. You could not bring that back, even if you tried."

"But what will it lead to? Arthur's death all over again?"

"Not with what you now know. Not while you draw breath." He put a hand on Merlin's shoulder. "Get some rest, Merlin. You will see it all clearer in the morning."

The girl moved restlessly on the pallet.

"I'll watch over her," Gaius said. "Get some rest."

...

Moonlight streamed through the window and Merlin lay awake in his bed. He was back in Camelot, Arthur was alive, and he'd bought himself some more time, even though he hadn't managed to lift the doom the Disir had foretold.

He should have felt joyful for at least getting a few more months at Arthur's side, but the joy was bittersweet. Months ago he'd hardly imagined his life without Arthur. Now it stretched ahead of him, long and empty. He was home, surrounded by his friends who were also his family and he'd never felt so alone. The knowledge he held was a bitter and empty cup.

He threw his legs over the side of the bed and resting his elbows on his knees he buried his head in his hands.

The main room was dark except the light from the fire. Gaius was asleep on his own bed and on the pallet by the fire, lay sleeping an unbroken version of the Bri he'd known. Merlin sat in the chair beside her bed and watched her. She was his only link to the other side, to the future he had fled. If he'd failed everything else, he hadn't failed her.

As if feeling his gaze on her, her eyes opened slowly and met Merlin's. They were the same warm amber Merlin remembered and he smiled at her and touched his hand gently to her pale cheek before realizing it was a mistake.

Fear filled her eyes and she jumped up and away from him. Desperate to get away, she fell of the bed and skidded across the floor in a clatter of falling furniture and jars. Gaius sat straight up in his bed.

"I'm not going to hurt you," Merlin said holding his hands out, but that didn't stop her. She stumbled about in the dark, until her back came up against the far wall.

"Merlin, you fool, what did you do now?" Gaius bellowed from his bed.

"Don't be scared," Merlin tried a second time, but Bri was watching him distrustfully and wouldn't settle down until Gaius came to her and sent Merlin away.

Lying on his bed, wide awake, Merlin thought it would have been impossible to feel worse, and now he'd proven himself wrong.

…

"Why so funereal, Merlin," Arthur teased him the following morning. "You're like a drowned rat sulking around." They were in Arthur and Gwen's rooms, and Merlin had brought in Arthur's breakfast and was now opening the curtains. Gwen had slipped out early while Arthur was still in bed. It felt so much like old times that Merlin could barely speak.

"If I was a drowned rat, I couldn't very well sulk around, could I?" Merlin attempted, but his heart was not in it. "I'd be dead."

"What is wrong with you?"

"Nothing."

He felt conscious of Arthur's gaze, but kept his attention on his chores. It broke his heart even now to be at Arthur's side, knowing that he'd still lose him.

"You were a bad servant to begin with," Arthur continued, "but now you're also dull. I'm not sure why I keep you?"

"I'm not sure either," Merlin mumbled.

"For goodness' sake, Merlin, get out! You're depressing me."

"Yes, Sire."

He walked away, feeling guilty for having made Arthur worry. For the life of him he could not bring himself to act the part he was supposed to.

"Merlin!" Arthur shouted behind him.

"Yes, sire?"

"If you're going to be a dull drowned rat, you might as well make yourself useful. Go make sure Guinevere's preparations are in order. She and Elyan will be journeying to their father's grave this morning."

Merlin's heart did a somersault. He was instantly on alert. They could not be allowed to go. Guinevere, captured by Morgana and kept in the Dark Tower under the power of the mandrake root, and turned against Arthur, had been a hard trial the first time around. He could prevent this. He had to try.

"Arthur, they must not go," he said and his voice was dead earnest.

Arthur was taken aback by the sudden change in his manner.

"Why ever not?"

"Please, Arthur, if you ever trusted me, trust me on this. They must not go. It's too dangerous. Morgana is too close to Camelot."

"Always afraid of your own shadow, Merlin..."

"Arthur," Merlin shouted, "for once in your life, please listen to me!" Arthur's eyebrows rose halfway up his forehead, but he stayed silent. "I don't say this because I'm an idiot or a coward, you know me better than that. I cannot explain it. I just... Please! Don't let them go."

In the silence that followed Merlin could hear his own heartbeat. He'd gone too far.