David slumped down into one of the jump seats near the console and buried his face in his hands, trying to reign in the chaos flooding his head, to sort through the myriad of thoughts, images, sounds, memories that threatened to burst through his skull. They weren't his, and thankfully, they were fading away; there was no way he could hold even a fraction of them. The worst part was the timestream. For a few moments after he had regained control, he had seen time like the Time Lords did, and though he couldn't comprehend a single bit of it, it had seared through his mind and its echo still lingered. He knew that Rory was standing next to him, concerned for him but uncertain what to do. And, he could hear, as if through cotton in his ears, Amy interrogating the Doctor.
"What'd you do to that Dalek?"
"Amy, later! We've more important things here."
"It's not going to come back, is it?"
"No! Look, we used the amplifier to send it as far away as we could. Beyond the end of the universe. Where it can't do any harm."
"But what happened to David? What did that thing do to him? What's wrong with him?"
"No, it didn't do anything. I did."
"You? What did you do to him, Doctor?"
"Something I did a very long time ago."
David struggled to his feet and brushed away Rory's attempts to help him. His vision was blurry, but he recognised the Doctor easily and pointed an accusatory finger at him. "You knew."
"Yes, I did."
David struggled to control his sudden rage, his whole body rigid. "You knew everything! Every single thing, all along! And you didn't tell me!"
The Doctor gazed at David, his expression a mask of sympathy, misery, and guilt. David shook as he held himself back with great difficulty from smashing that face with his fists.
Amy stepped between the two men, to prevent the apparently looming fight. Facing David, she called over her shoulder, "What's he talking about, Doctor? What did you know?"
"This." David stuck his hand in his coat pocket and pulled out a small brass disc-shaped object: a pocket watch, complete with fob chain. With a contemptuous flick of his wrist, he tossed it to Amy, then spun away, clenching and unclenching his fists as he fought to calm himself down. Inspecting the watch, Amy touched the Gallifreyan symbols etched on its cover. As she positioned her thumb to press the latch, he cautioned her, "Don't open it." His back was still turned.
"What is it? Obviously it's not just a watch."
"It's me. The real me." Turning back to her, he held out his hand for it, and she dropped it in his palm.
"What does that mean?"
Rory placed a hand on Amy's shoulder. "It means he's the Doctor. Actually the Doctor."
"What?" She stared at Rory in disbelief. "But he said he wasn't!"
"He didn't know. He only found out when the Dalek appeared."
"No! That can't be..." Turning to David, she gaped at him, eyeing him up and down. "No. You were just acting, right? That's what you do. You were playing the Doctor, like your show on the telly."
"No. I am the Doctor." He enunciated it slowly, as if trying to believe it himself. "I think I knew when I looked into Donna's eyes." David shook his head to clear the memory of his best friend's face as she died, and stared at the watch. "But I didn't want to admit it. Then the Dalek had the Doctor trapped and it was hunting for you, and we tried to find some way to help. Then he took over. The Doctor took over." He touched the cover of the watch with one finger, then rubbed the back of his neck. "I had to let him. It wouldn't have worked, if I'd tried to stop him. We would have been fighting each other. I had to let myself go, let him take full control. We couldn't have saved you otherwise."
He looked up at Amy, frightened and despairing. "I'm still me. I'm still David. For now. Until I open this watch. Then the Doctor comes back and I'm gone." The anger returned, swelling up inside his chest, and he glared past her at the Doctor. "But you knew. From the very beginning. From the moment you installed the paradox circuit."
"Yes. That's the moment I remembered everything."
"You said you were closing the rift, but you were actually making a paradox machine!" David stepped to the console and, gazing sadly, lovingly at the time rotor, stroked the glass cylinder. "What has he done to you?"
The Doctor also placed a comforting hand on the console. "Only a little one. Very localised. A tiny bit of what the Master did. It was the only way to keep the anomalies from tearing her apart."
Still staring up at the column, David cried, "You could have taken me back home!"
"You know I couldn't. My existence depends upon you being here."
David gritted his teeth. The Doctor was right, but he didn't want to admit it. "So, you pretended all this time that you didn't know what was happening. You lived through it all as me, and just did it all over again. You led us into danger you knew was coming, and you let me stumble through it all, let me hurt people, and you just let me suffer! You even let Donna die!" His throat choked up on that last sentence.
"Yes. I had no choice." The Doctor's expression was impassive, but his eyes betrayed sympathy for David's despair. "The events already happened for me. I couldn't change them. That's the nature of the paradox. You understand that better than any other human does. You know what would have happened if I tried to change anything. I had to do what already happened." With tired, bent shoulders, he pursed his lips, shaking his head. "This time, I was the actor."
Whirling around, David stomped back to the jump seat and slumped in it. Rubbing his face hard with his hands, he tried to reject the universe around him, tried to prove that he wasn't here and he was simply just David; even being in a coma after that car crash would be preferable to this. But reality never wavered, and his too-rational mind had already deduced his inevitable fate. He looked up at the Doctor, and spoke in a weary, hopeless voice, "I suppose the very fact that you're standing in front of me tells me what I have to do."
The Doctor nodded.
David leaned back in the chair and snorted a laugh, though he spoke with a slight sneer. "And you're standing there with the most neutral face you can keep, so that you don't tell me when."
"You have to work it out on your own, when you're ready. You know that."
"Yes. I do." David jumped to his feet and puffed out a breath. "Okay. You and I both know that once the paradox machine is turned off and the timestreams realign, I'm going to forget everything to do with this paradox, all of this life, until I build it again when I'm you. So, tell me. Why?"
David threw his hands up. "Why everything!" Angry and agitated, he strode around the console. "Why wouldn't you just tell me? You knew where the watch was! Why didn't you just give it to me and be done with it? Why did you let me continue living this lie? And why did you use the arch in the first place? How, for that matter?" He halted and spun toward the Doctor. "I remember my life, all of it. My existence might be just a Time Lord's fever dream, but it isn't just a litany of facts, like John Smith's was."
The Doctor began pacing back and forth as he spoke. "The 'how' is easy. I am very clever. I built a regressive transcoder into the arch, and made myself into a human child. To live an entire life, not just insert myself somewhere. As to why I did it…" He stopped and turned to David, wagging a finger at him. "I know that the last person your Doctor met on your programme was Jackson Lake, which means you never got to see what happened later."
The Doctor's shoulders drooped. "I made mistakes. Big ones. I knew that I'd lost control, forgotten who I was and what was important. So I ran away. I chose the best way out I could think of: live a normal life, die a normal death. The one thing I could never have. I wanted your life. I never intended to come back.
"I suppose the TARDIS is really the one that saved me, creating the paradox to come to get you when she did." As he spoke, he glanced at the console, his love for the machine evident in his eyes. He shook his head slowly, then caught David's gaze and held it. "But I had to let you live through all of this, so that you would learn again what I had forgotten: what it's all about, why we do it. Why it's worth the price we pay. Why we have to keep fighting the darkness inside."
David frowned, confused. What had he supposedly learned? He'd just tried to do the best that he, a simple human, could do. Nearly messed up a couple of times, almost got himself and the Doctor killed. The only truly resourceful thing he did, the Doctor had been in control, not him. "I don't understand."
The Doctor placed a comforting hand on his shoulder. "No, David, you don't. For once, you don't understand, and that's okay. The Doctor, your Doctor, he understands and he learned it well, by watching you do what you knew to be right, even in the worst circumstances. That's what he needed to learn. I know he has, because I did."
David stared at him in disbelief. He could not comprehend what the Doctor was talking about, why the Doctor would have anything to learn from him, and he realised that he wasn't meant to: the moral was intended for the Doctor and he, David, was simply the storyteller. There was one thing he did know, though. "But it doesn't matter anyway, does it? I'm just going to forget it all the moment the paradox circuit is turned off."
"No." The Doctor emphasised each of his phrases with a thrust of a hand. "No, you won't. You'll forget what happened, yes, but you will remember what we learned. It'll still be churning in the back of your mind after the timestream returns to normal. And you will need it, for what's to come."
The Doctor's words frightened him, and a cold hand gripped his heart. "Why? What's going to happen to my Doctor?"
The Doctor shook his head, his eyes ancient and sad. "You'll find out, soon enough."
The Time Lord whirled and walked away, and David knew that he wasn't going to reveal any more. Pressing the matter wouldn't change his mind. He turned away, too, striding to the edge of the console platform, his hand covering his mouth as he tried to sort through the jumbled mess in his head.
The Doctor and David stood on opposite sides of the console, backs to each other, while Amy and Rory watched them both, exchanging uncomfortable glances as the silence wore on. Amy finally elbowed Rory and jerked her head towards the nearest hallway, and together, they crept toward it as quietly as they could.
"No. Don't go." Turning to face them, David stretched one hand out in supplication. "I want to say goodbye."
Amy and Rory were astonished, and their jaws dropped in unison. "You're going to do it now?" Amy spoke for both of them.
David nodded, his expression impassive. "I have to. I'm going to do it. I've already done it." His eyes flicked towards the Doctor for a moment. "The only question is when, and I don't see any reason to delay."
"But…" Amy's eyes glistened. "But what happens to you, when you become the Doctor? What happens to David?"
He cast about for a way to explain it easily. "It's complicated. I'm... I'm just another facet of the Doctor. That's all I am." That was one of the hardest things he had ever had to say. "When the Doctor comes back, I won't be me anymore. I'll be gone, and I'll be the Doctor, but I'll still be there. If that makes any sense. Isn't that right, Doctor?"
"That's right," he answered, turning around and leaning back on the railing. "I still hear you, in here" - he tapped his head - "along with everyone else I've been. Quiet, but there. Well, mostly quiet. Sometimes you lot make quite a racket."
Amy waved her hands, wiping away the distraction. "No, wait. How can you just say that? How can you just throw yourself away like that? You sound like you're volunteering to jump off a cliff. You sound like you want to die."
David fiddled with the watch, weaving the chain around his fingers. "I suppose I do, in a way, because I don't really have a life, not anymore. I left my life in another universe - my home, my family, my friends, my job, even. And even if the Doctor could take me back there, I couldn't go back. Not after the wonders of all of this. Pretending to be the Doctor on a fake set, after being him, standing on the threshold of the TARDIS, floating amongst the stars? Nothing could compare."
His breath stuttered as he inhaled deeply. Both hands closed around the watch. "Really, though, I don't want to die. I'm scared. Frightened out of my head. Every instinct is telling me to run away, to save myself. But I know I have to go. And look at what I become!" Shaking, he gazed at the Doctor, tears starting to spill as he tilted his head with an expression of pure wonder. "The renegade Time Lord. The wandering god. The man who soars through time and the universe, saving people and planets without a thought for himself. My hero, all my life." He turned back to Amy. "If that's who I am, if I'm just a story that'll help him remember who he is and why he does what he does, well, that's a magnificent legacy."
Sniffling, he smeared away the tears on each cheek, then held the watch up in front of his eyes on the tips of three long fingers. "He calls to me. I can hear him. My head is filled with his song. I could wait more, but really, it's time he took back his own." Letting the watch drop into his palm, he squeezed it hard in his hand.
Amy sprung forward and threw her arms around David, hugging him tight as her tears dotted the collar of his coat. "Goodbye, David. Oh, I don't know how you can... I could never do this."
David embraced her and, closing his eyes, buried his face in her copper hair, savouring her human warmth and scent, the last he would ever experience. He swallowed to suppress the shuddering in his chest and patted her lightly on the back. "Sure you could. What wouldn't you do for the Doctor?"
Pulling back, she held his shoulders at arms' length, regarding him sternly. "While you're in there, tell him to get rid of the bow tie."
David's eyes lit up, and he grinned at her affectionately. "Do you think he'd ever listen to me at all?"
"He would if he knew what was good for him."
"Goodbye, Amy Pond." She smiled through her tears, and as she stepped back, Rory took her place.
"David." He swung his arms nervously, gazing down and away from his friend for a moment, before finally giving him a brief, awkward hug.
As they separated, David grasped his hand. "Rory. My friend. Farewell. Thanks for everything."
"No, thank you." Stepping back, Rory wrung his hands as he spoke. "For doing what you did. I saw you: you didn't want to, but you let it happen. You gave yourself up, to save Amy. It's everything to me."
"It was my honour. Don't ever let her go."
"I won't." Rory's cheeks twitched a tiny smile, then he sidled over to stand by Amy, taking her hand in his.
David turned towards the Time Lord, who was still standing on the other side of the console platform watching him with an inscrutable expression, and nodded once at him.
David held the watch in the palm of his hand and lightly traced the symbols on the cover with a trembling finger. Swallowing nervously, he inhaled deep into his chest and let his breath issue slowly from his mouth, then flicked the latch with a sudden jerk of his thumb. The cover popped open and ethereal light bathed him; the last things he saw were tendrils of golden energy snaking from the watch towards him, caressing his face. As his eyes closed, the consciousness of the Doctor enveloped his, the timestream of the universe blossoming into his mind, and David was no more.
Author's Note: Thank you so very much for reading this story! I hope you have enjoyed reading it as much as I have enjoyed writing it.