A/N
This is my version of what happens after The Doctor leaves Rose and The Human Doctor behind on Pete's World. Just pretend that Mickey and Jackie didn't follow Rose from Pete's World. Please enjoy and review! :)
Rose Tyler stood there and watched as the TARDIS slowly dematerialized from the beach. Leaving her behind. Again. This couldn't be happening! Not after all she'd gone through to get back to him, to find him again. Beside her, the Human Doctor reached down and took her hand. Rose looked up at him as the TARDIS vanished completely. He had told her he loved her. What The Doctor hadn't been able to ever actually say. But she had known – she could feel it. The way he looked at her and held her hand. Rose looked over at The Human Doctor. She had kissed him. She was so confused. This man beside her, he looked like The Doctor, thought like The Doctor, acted like The Doctor, sounded like The Doctor, but he wasn't The Doctor. Was he? The Human Doctor watched her, seeing the confusion on her face and understanding how torn she must be feeling right now. To be left behind with a clone. If she let him, he would never leave her. But if she really wanted, he would go. He didn't know where – without her his life would mean nothing. In a way, he had been created for her. But he didn't want to push her. After a moment, Rose said quietly,
"But you're not him." The Human Doctor nodded, understanding.
"No. I'm not." He said just as quietly. "Not exactly. I look like him, I talk like him, I even have the same memories. But we aren't the same." Rose looked down, but The Human Doctor tilted her chin up so that she was looking at him. "I'm human. The way I think, the way I act, all have traces of humanity I picked up from Donna." Rose nodded. The Human Doctor hesitated then continued. "But one thing will never change. I told you I loved you and I meant it. If you let me, I'll never leave you." Rose just looked at him. The Human Doctor could tell she was having an inner argument. He didn't want to push her into this, but he reached down and took her hand again, savoring the way their hands felt so right together. Rose closed her eyes then looked down at their intertwined hands. The Human Doctor unconsciously held his breath, waiting. Then she smiled at him. Not her megawatt grin, but it was a smile.
"Come on." She said. "Let's go. I hate this bloody beach."
They walked hand-in-hand, just talking. Figuring out things between the two of them. The Human Doctor could have fixed the Dimension Jump Rose carried to work as a teleport to take them back to Torchwood with the sonic screwdriver Rose had picked up form the parallel world she had been in with Donna. But Rose had told him no. The walk would give them time to figure things out. They took turns telling what had happened to them since Rose and The Doctor had last been together. The Human Doctor told Rose all that had happened to The Doctor since she'd left. He told her about Donna, about meeting Martha, and the return of Captain Jack Harkness, universal flirt. She had laughed at that. He told her about the Year that Never Was and the return of The Master, and she cried with him. He told her about how Martha had left and how Donna had found him again. He told her about Pompeii and the Adipose, about the Library and about River Song. He told her everything, leaving nothing out. But most of all, he told her what it had been like for The Doctor after he'd lost her. How he'd been lost without her, his whole world shattered. In return, Rose told him what had happened to her. About that first month when she wouldn't leave her room. About how she finally began working at Torchwood and all those long nights trying to get the Dimension Canon to work without it destroying both Universes. About the birth of her younger brother, Tony. She told him about the stars going out and how the Dimension Canon suddenly started working. She told him about all those parallel worlds she had searched for him in. Some had been wonderful. She laughingly told him about the one where he was still all big ears and leather and she had been mistaken for the parallel version of herself. That had been an adventure. Some had been nothing exciting, and she'd quickly moved on. But some had been terrible. She told him about the parallel universe that he had been in with Donna. How he had died, and so had Sarah-Jane and her kids, and Jack, and Martha and how she had knowingly sent Donna to her death. Just because Donna had turned right. And she hadn't been able to save them. Any of them. The Human Doctor held her tight, sharing her pain. They kept walking and The Human Doctor told her how he planned to grow a TARDIS from the chunk of coral The Doctor had given him. With Donna's suggestion, they could have a functional TARDIS within a year. It wouldn't be fully grown and they would be limited to how far they could go in the beginning, but it would be functional. And as they traveled, their TARDIS would continue to grow.
"You and me. In the TARDIS." Rose said with a smile. "Just as it was meant to be." The Human Doctor grinned back at her.
"The stuff of legends."