He looked at her and smiled. His heart swelled. A tear came to his eye as he reached out and grasped her hand. Even in her sleep, her fingers instinctively gripped his. His smiled widened farther. He was so happy, so ludicrously happy that sometimes he couldn't believe his luck.
He thought back to the day that had started it all, the day he was created. The moment he saw Donna, he knew what had happened. He knew that he was some sort of a copy. He didn't get too much time to dwell on it in that moment, though. The TARDIS was floating towards an inferno and, as he and Donna were still inside, he needed to get it up and running as soon as possible. Once they had reached safety, he let his brain carry out his actions, as usual. He had no idea that his heart was in it as well.
He should have realized. He should have known that he wasn't thinking objectively, but he was so absolutely blinded by his emotions. He was concerned for Donna, who had almost died because of him. He was terrified for Rose, being held hostage along with his other self. And he was angry. He was so very angry because Davros was back.
Davros.
The man who had started it all, the creator of the Daleks, the very source of the last great Time War. It had been bad enough that the creatures themselves had survived while the Time Lords had not, but this – the fact that Davros had been pulled out of the depths of a time lock – was completely unbearable, for while he lived, so too did the Daleks. He needed to be destroyed. His creations needed to be destroyed. The Doctor had eliminated everything, the entire Dalek race, all of the Time Lords, even both of their home planets! And yet here was Davros with yet another fleet. The newly created metacrisis refused to have a repeat of the war that had taken everything from him.
These thoughts consumed him as he ran around the console, piecing together a makeshift weapon that would end Davros forever. The second he burst through the TARDIS door, his senses zoomed in. All he could feel was the weapon in his hand. All he could see was Davros, and all the while, the screams of his people as they and his planet burned rang in his ears. He broke into a run, closing the gap between himself and the man he needed to defeat.
He didn't think, he merely acted, which was exactly how he wound up trapped, stuck in the same type of prison as his other self.
But there was still Donna.
She suddenly came to life, creating and enacting plans that neither he nor his original would ever think of. She had done what he couldn't do, and yet she wouldn't do what he knew needed to be done. Her primary focus was overcoming the Daleks, breaking the force fields and returning the planets to their original locations. But when the original had wandered into the TARDIS, he did his part, completely eliminating the Daleks and their crucible. Davros went along with them. He was determined to never have another run-in with his fiercest enemy ever again.
They stopped in London to drop off Sarah Jane and Jack and Martha. Mickey snuck in there as well, understanding that he had more to gain in this Universe. Then they moved to the parallel Universe to drop of Jackie, at least, he thought it would be just Jackie. As soon as they landed, he wondered how it would work with himself and his original and Rose all aboard the TARDIS. Having all the same memories and the same emotions (just a little closer to the surface in his case), he knew that his original loved Rose as much as he did. The mere thought of Rose staying was enough to start a crack in his single heart. She would never choose him over the other, and he was painfully aware of that. If he stayed on with them, his one, lonely heart would completely sever in two. On the other hand, if Rose decided to leave, which she would never do, he would go as well. Knowing he was partly human, that he no longer had a few hundred years to spare, made him want to do things that he hadn't done in centuries. He wanted to love openly, to be happy. Travelling didn't matter so much. He had done that long enough. And he wanted Rose. More than anything, he wanted Rose, and, if she let him, he would do anything to keep her with him forever. Their forever, not hers, theirs.
In the end, neither of them was even given the choice. His original had decided to sacrifice his hearts and his desires in order to keep Rose both safe and happy. He was leaving them both in the parallel Universe. Instantly a twinge of anger overtook the metacrisis. Why was it for the original to command the copy? They were the same person with the same memories and appearance and damn near identical thoughts and needs and wants. Why couldn't he choose his own fate?
Rose had tried to fight it, the memory made him chuckle slightly. She had worked so long and fought so hard to be with her Doctor. She wasn't just going to let one of them make her decision for her. Whichever one she stayed with, she stayed with them because she said so. The fact that the copy would grow old with her meant nothing. There was one thing she needed to know. "Yeah," she had said, "and how was that sentence going to end?" She looked to the original first, and he opted to pass. He knew that if he spoke the words, his copy wouldn't stand a chance. But now here it was. The metacrisis was finally able to say the words that had been in the Doctor's head almost from the very moment he had met her. He leaned in and breathed the words into her ear.
And she chose him. She turned and gripped his lapels, slamming their lips together. After a moment, just a moment, he wrapped his arms around her, returning her affection whole heartedly. Suddenly they heard the TARDIS. She broke the kiss and ran towards the noise. At first he was afraid that she regretted her decision, even this soon after making it. But when he walked over to her and connected their hands, she didn't let go. On the ride to London, she didn't let go. She refused to let him sleep in the guest bedroom that night and when he woke up the next morning at her side, in her bed, they were still holding hands.
It was difficult at first. They fought a lot. He was so scared that she wouldn't love him, couldn't love him because he wasn't the "real" Doctor. She herself was confused about if he was the Doctor or a completely new person, and, because of this, she wasn't sure how she felt about him or what she felt for him. It took months and a lot of talking and a lot of honesty before they finally found level ground and began to build a relationship and eventually a life together.
Having their own TARDIS helped as well. At first they mainly stayed in England, travelling only through time. He needed to learn more about the different planets in this Universe. They might have different histories or maybe one century that was peaceful in the other Universe was dangerous and war-torn in this one. Maybe the cultures had developed differently and were more or less advanced than when he knew them to be. Once he had a substantial list of planets and their safer centuries, he and Rose added space to their travels. It was a nice change to be able to learn about a planet right alongside her.
They primarily travelled on weekends, trying to keep the time spent in the TARDIS synonymous with the passing time of the Universe. During the week, they both worked at Torchwood. She specialized in alien relations, he in alien technology. He went by the name John Noble. When deciding on a name, Rose had first suggested that he go by John Smith, as was his custom, saying that the name John suited him. But he knew something that she didn't, and he felt it only right to pay some sort of homage to Donna, for without her, he wouldn't exist. Rose understood what Donna had done, but she could tell there was more to his reason than that, so he explained.
When the TARDIS had vanished, leaving them on the beach, John felt sadness overcome him. He knew that the Doctor was performing the most difficult act of any of his past selves. Giving his life for Rose had been a no-brainer. The choice between eternally punishing the Family of Blood and leaving them to die had been even easier, but Donna's case was a lose, lose. Her mind wasn't built to house the Time Vortex. It wasn't strong enough, and if it wasn't removed, she would die. But if the Doctor locked it away, pressed it so deep into her subconscious that it would take everything to make it reappear, she would survive. He would have to lock everything else away as well, including the memory of him and everything that they had done. She would never know how she saved the whole of reality, how everything still existed because of her. John knew full well which the Doctor would choose, and he didn't hold any envy for what he had to do.
When he had finished explaining, Rose felt no desire to hide her tears. He held her close as she proclaimed over and over about how unfair it was.
Eventually they were able to put the events of that day in the past. Between their work and their travels, moving forward was a relatively smooth process. But they never forgot. They made sure to never forget. Once a year, on the anniversary of the day they were left there, John Noble and Rose Tyler would go back to that horrendous beach and reminisce about the year that had passed, hoping that maybe, just maybe once there would be a pin prick in the walls of their Universe, just a little opening that would allow their stories to make their way to the Doctor's ears.
On their third visit, they stepped on the beach as John and Rose Noble. Never had they wanted to be heard so badly. They wanted to let him know that his sacrifice hadn't been for nothing, that he had done the right thing because they had truly chosen forever and they were incredibly happy.
John was ripped back to the present as the hold on his finger tightened, and he realized that her eyes were open. The smile returned to his face, and he leaned over to press a kiss to her forehead which caused her to emit a short giggle.
"Hello," he cooed softly. "Did you have a good nap?" With a smile, she kicked her legs in affirmation. "Let's go find mummy, then. I'm sure you're more than ready for an afternoon meal."
He picked up the infant and made his way to the kitchen where he found his wife glancing at a magazine. She heard her husband's feet shuffling in the living room and looked up in time to see the pair of them come through the archway. She grinned and muttered a greeting before placing a brief kiss on his lips and lifting the babe from his arms. John leaned against the counter as Rose maneuvered around the kitchen to grab a prepared bottle. It was moments like this when he felt a small ache of guilt through all his happiness. Who knew what the Doctor had faced since leaving them those four years ago. Had he regenerated? Was he travelling with someone? He had lost anyone? Did he still think of Rose? Did he regret leaving her?
Soon, John knew he would make peace with not knowing, but as small of a chance as there was, he hoped that one day he and Rose would get a message through and the Doctor could be content with the images of the life and bliss of John and Rose and Tanya Donna Noble.