Author's Note: Last chapter! I swear, I would literally marry both Rose and the Doctor at the same time. Thank you so much for reading my fanfiction.
Her breath came quickly. "That's not possible, Doctor." Was it?
"Rose," he countered, laughing in delight. "how many times have we said that, only to have the impossible happen before our eyes? Think about it! It's only logical that you're immortal if you could survive being pulled through dimensions, the Void, and free space to reach the TARDIS. It's the only thing that makes sense."
"But how?" She croaked, her head still spinning from his declaration.
The Doctor shrugged, still grinning. "My guess is that the energy of the Time Vortex bonded with a part of you at some point while you held it in your body. Perhaps, when you used its powers to resurrect Jack, it latched onto your cells, and made you, for lack of a better word, invincible to death."
Rose was silent for a few moments, needing to process. Finally, she muttered, "I-I can't die?"
He shook his head. "Or get older. Physically, anyway."
She sat heavily in the TARDIS's jumpseat. "Then, I can really stay with you? Forever?"
He grinned wider. It was a smile so large that it threatened to split his lips. "If you want to. You may even outlive me, but then you can find Jack. Don't you see? You'll never have to be alone again. And you can see everything change and grow, just like I have! Rose, this is fantastic!"
"But, I can stay here on the TARDIS with you forever?" She repeated.
He sobered, "That is, if you want to. You could stay for two forevers if you wanted to."
She stood then and threw her arms around his neck, before slamming her lips against his. He was taken by surprise, and it was a moment before she felt his hands lock around her waist, jerking her tightly against him.
Rose poured every ounce of passion that she had into her kiss, reveling in the feeling of just kissing the Doctor. There was no danger, no ulterior motive. It was just her and the Doctor. Her Doctor. With this kiss, she showed him every moment of pain that accompanied the memories of losing him. She also shared an intense feeling of happiness with him as they realized what their newfound compatibility meant. Kissing him under this circumstance was unlike any kiss that she had ever and would ever experience. For the first time in a long time, she thought of him as alien, because only an alien could share a level of intensity such as this in something so trivial as a kiss.
She gave a tiny laugh between kisses as she realized that she, too, was now alien to some degree. No normal human would ever have the promise of eternal life in the manner that she did. The Doctor laughed to, before gently rejoining their lips.
The Doctor's hands fluttered against her lower back, the intensity of what he felt for her, and she for him nearly overwhelming him. Her soft lips fit against his as if she had been born to kiss only him. Her fingers running gently through his hair brought about a tingling euphoria so powerful that he felt a hot bead of moisture form in the corner of his eye.
She was there, and she would never be gone again. He would never, ever be alone again, because she could stay with him until the end of his days, and he would never have to the bear the pain of watching her age and eventually die. They would be the same, the Doctor and his companion. They would make their mark on history and the universe together. The realization had him grinning against her lips.
After several moments, she pulled back from him, leaning her forehead against his. "Doctor?" She whispered, reverently. Her hands rested on his chest, and she could feel the binary circulatory system that she had missed in every embrace she had received on Pete's world.
"Yes, my dearest Rose?" He answered, his hands stroking her back through the thin cotton material of the dress.
"I love you."
Unlike the day at the beach, and unlike every one of her pretend conversations with her Doctor, her profession of love was not followed by silence.
"Rose Tyler, I will always love you."