a/n: And now finally a few answers and a little good news.

Chapter Twenty

Rose woke up in the middle of the night to find the Doctor wasn't in bed. She wasn't particularly surprised. Since they had moved to Cardiff, he had always gone to bed at the same time she did, but he usually got up for a few hours in the middle of the night. Most nights he only needed about four hours of sleep, so he spent much of the time while she was asleep either stargazing if the night was clear or working in his lab if it wasn't. He usually returned to bed in the early hours of the morning so he'd be there when she awoke.

Having gone to bed earlier than usual, Rose was wide awake and decided to go look for him. She did it occasionally; after finding him, they'd often share a midnight snack or she'd coax him back to bed. It took very little effort to coax him back to bed, often just a look, a raised eyebrow and a small smile. Based on the time they had spent in bed before she had fallen asleep, she guessed they might be sharing a snack, but maybe not. For someone who had lived like a monk for most of his long life, this version of the Doctor had a very healthy libido. A very, very healthy libido. And she was extremely happy about it.

She got out of bed, pulled on some clothes and wandered down to the kitchen. Nope, he wasn't raiding the refrigerator. And he wasn't watching telly either. Well, she hadn't really thought he would be. If the skies had cleared up after the storm earlier, he could possibly be in the garden with a telescope. She slipped on a pair of trainers and went outside.

The air was cooler than it had been in weeks but it was still muggy and the sky was still thick with heavy clouds. He obviously wasn't stargazing tonight. He had to be in his workshop, she told herself, and she headed in that direction.

Large puddles had formed in the low areas of the driveway, so she walked through the grass to avoid them. Water dampened the bottom of her jeans and seeped through her trainers, making her socks uncomfortably wet.

As she neared the former barn, she saw light streaming through the small windows on the side closest to the house. Certain she had found him, she crossed to the door, tiptoeing around the puddles in the drive. She called to him as she entered.

"Doctor?"

But there was no answer.

Unlike it usually was when he was in his lab, the building was silent; the only thing she could hear was the hum of his computer and the overhead lights. Normally there was some sort of noise with whatever he was working on, and when there wasn't, he was usually whistling or talking to himself or something.

"Doctor?" she called again. When he still didn't answer, she glanced around in concern.

Everything in his lab looked exactly the same as it always did: the incomplete projects laying on tables and benches; the shelves filled with spare pieces of equipment and alien tech; and the bin that was filled with pop cans, biscuit wrappers, and banana peels.

The Doctor sat frozen in front of the computer, staring at the screen. She had never seen him so still, not in any regeneration she had known. And this Doctor, even more than the others she had known, was almost constantly in motion: walking, running, bouncing on his toes. In those rare instances where he was required to sit, he would drum his fingers on his knee or the armrest of his chair or he'd tap his foot on the floor. Even while he was asleep, he wasn't completely motionless like this.

It was so out of character it was almost frightening.

Rose walked up to the desk and knelt beside his chair.

"Doctor, what's wrong?" she asked, laying a hand on his arm.

The Doctor started. "Oh, Rose, sorry, I didn't hear you come in." He leaned forward and shut down what he had been doing on the computer. "Nothing," he said quietly. "It's nothing."

But she knew him too well.

"No, whatever it is, it's not nothing," she argued.

She took his hand, interlacing their fingers and rubbing his knuckles with her thumb. With her other hand she reached out and caressed his face, tracing along his sideburn and jaw with her fingertips. He closed his eyes and leaned into it.

And then Rose noticed that the grow light that always glowed over the tank that held the TARDIS coral was off.

"Doctor," she began, "why'd you turn the light off over the TARDIS coral?"

He sighed, so quietly she almost missed it. "Because the TARDIS coral is dead."

"What?" she gasped.

"It didn't work. It couldn't make the energy transition from that of our original universe to this one. It came from our original TARDIS, and you know the TARDIS couldn't function with the energy available here." He took a deep breath and let it out slowly. "I couldn't do it. I tried everything I could think of, but I couldn't do it. I'm sorry, Rose. I wanted to give you the stars again, and I can't."

She heard the pain in his voice, and she fought the tears that sprang to her eyes.

"Doctor, I don't need that," she said.

"But I know how much you wanted to go with… him," he said and swallowed hard. "And there's so much that he could give you that I… can't. I wanted to give that to you. I know how much you loved when we were traveling."

"Doctor, listen to me. I loved traveling with you," she told him. "I loved going to new places and new times. But it never was just about the traveling. It was about being with you. From the very beginning, it's always been about being with you. I just wanted it to grow for you," she continued, "so you wouldn't have lost the stars as well as everything else."

He stared at her, eyes suspiciously bright, and swallowed thickly. "Oh, Rose Tyler…" he began, but couldn't finish the thought. Lifting a hand to her face, he caressed her cheek with one finger and bent to kiss her forehead. "I haven't lost everything. I have you, and that's more than I could have ever wished for."

~oOo~

Rose woke up early the next morning to sunlight streaming in the window, hitting her full in the face. She crawled out of bed and, after closing the curtains so the sun wouldn't wake him, she slowly showered and dressed. At some point she was due to go in to work, but she didn't need to be there yet and after last night she hated to leave him alone.

Thankfully, the Doctor was still sound asleep. After he had told her the news about the TARDIS coral, she had coaxed him back to bed, where they had talked about their future. He had put a brave face to it, talking about traveling Pete's World, but she knew he was devastated, and shortly after he had fallen asleep he had had a nightmare, the first one he had had in weeks. Just as hers were finally abating, his seemed to be returning.

Once downstairs, she filled the electric kettle with water but before turning it on she decided to go outside for a few minutes. Before she knew it, she found herself at the Doctor's workshop.

Rose hesitated at the door. She had never been in it without him being there before. It wasn't a question of being allowed to be there alone, but it was his inner sanctum, his place to work on his own projects and research, and she respected his privacy even though he had never asked for it. But she felt drawn to the lab this morning. She wanted to see the TARDIS coral for herself, and she wanted to do it alone.

Once inside, Rose crossed to the darkened tank. She took off the lid, reached in and pulled the coral branch out of the moist sand it was half buried in. She gently, gently brushed off the loose sand with her fingertip before pulling her hands out of the tank.

It was heartbreaking to think that the coral was dead. Not for herself, but for him. The coral was the last, the only link to his past life he had, and it had been his hope for their future. She would do anything, give anything, to give that hope back to him.

As she held the small branch of TARDIS coral, it began to very, very faintly glow with a golden light. She gasped as her heart began to pound and in her shock she almost dropped it. She hadn't handled the coral since she had first set it up in its tank while they were still at the mansion, and it certainly hadn't glowed then.

The light faded almost immediately.

"Please, please, do it again," Rose begged but it remained dark.

Carrying the coral, she walked over to a chair in a shadowy corner of the room and sat down. She must have wanted it to be alive so much that she had just imagined it glowing, she told herself. That was the only explanation. The sunshine coming in from the window must have bounced off something in here and hit the coral, illuminating it.

But what if she hadn't imagined it?

She held it, only inches from her face, close enough that she could see every nook and cranny on its rough surface, and willed it to repeat its performance. Slowly it began to glow again, this time more brightly than the last. And here, in the shadows, there wasn't any sunshine bouncing off of it. She giggled, not quite believing her eyes.

Almost unable to contain her excitement, she rushed to put it back into its tank. She then raced back to the house, not bothering to close doors on her way, and ran up the stairs to their bedroom. Once there she jumped onto the bed, causing it to bounce up and down a bit. The Doctor groaned and began to stir.

"Doctor, Doctor, wake up!" she said urgently. She grabbed his shoulder and shook it.

He blearily opened one eye.

"Wha'?" he said, yawning. "What is it?"

"Wake up!" she repeated.

"Blimey, Rose," he complained. "Give a man a chance to sleep, will you?" He buried his face back in his pillow.

"No, you need to come now," she told him firmly, jostling his shoulder again. "Consider it payback for all the times you woke me up in the TARDIS."

Groaning again, he sat up and scrubbed his face with his hands. "You do know I've only been asleep two hours, thirty-eight minutes and forty-three seconds, don't you? Even I need more sleep than that."

She stared at him impatiently. He was wearing what he had worn to bed, a tee and boxers, his hair was a mess and he was in need of a shave. He was so sexy that way that part of her just wanted to climb back into bed with him, but this was way too important.

"C'mon," she ordered. She grabbed his trousers and socks off the floor and tossed them to him. "Get dressed and come with me."

He pulled a face. "Not only do I have to be awake but I have to be dressed, too? What's going on?"

"You'll see."

Once he had finished getting dressed, she grabbed his hand and dragged him out of the house and to the barn.

"What…" he began.

"Doctor, just wait," she said, pulling him inside the building. Letting go of his hand, she walked to the tank and picked up the small branch of TARDIS coral. As it had before, it began to shine with a golden light.

Now fully awake, his jaw dropped and his eyes widened in shock.

"What?" he said again.

"It's, it's glowing," Rose said unnecessarily. "When I pick it up, it glows."

"What?!" he said a third time, his voice tinged with hope.

"Doctor, it's glowing!"

"I don't believe it! How? I thought…" His face broke out into a wide grin and she grinned back. Pulling his sonic screwdriver out of his pocket, he scanned the coral. After examining the readings, he gingerly took the coral out of her hands and placed it back in its tank. Then he gathered her into a huge hug, picking her up and swinging her around in a circle as they both laughed in happiness.

Then, to Rose's surprise, he abruptly put her back down on the floor and stuck his nose in the crook of her neck, inhaling deeply. Before she could ask him what he was doing, he grabbed her hand, sniffed her palm twice, and then licked it.

"What the hell…" Rose began, but was unable to finish the thought as the Doctor grabbed her face and began to kiss her, thrusting his tongue deep into her mouth. Taken aback at first, after a second she began to kiss him back but was startled when he let go of her, almost pushing her away. He stared at her, brow furrowed and openmouthed, a look of total shock, and possibly horror, on his face.

"What? No…" He kissed her again and then pushed her away, only to lick his lips. "Oh, you're kidding me! No…"

"Okay, what is going on?" she demanded. "Because this is weird, even for you."

"Artron energy," the Doctor said, still staring at her in shock. "You, Rose Tyler, are full of artron energy." He closed his mouth, moving it around as if he were tasting something. He nodded. "Artron, Void, with just a hint of huon radiation, chronal energy and Time Vortex." He grimaced, running his hand through his hair and beginning to pace. "Why did I miss this? How did I miss this? Why did I not know this? After all this time…" he muttered.

"Doctor, what is it?" she asked.

"Well, that explains the healing, the lack of scarring," he said. To Rose's ears, it sounded like he was still talking to himself. "But I was so sure…. Granted, there were extenuating circumstances, and I was a little distracted at the time, what with regenerating and all…. But still, how could I not notice?" He stopped and rubbed the back of his neck, and then tilted his head and peered at her as if he were examining an intricate puzzle, or possibly an alien creature. "On the other hand, it's not like we did a lot of kissing back then, hardly any at all, really. Well. Maybe if we had I would have noticed sooner." He furrowed his brow. "But still, I should have noticed before now. It's not like we haven't been doing a lot of kissing lately. Well, more like snogging actually, brilliant, really brilliant snogging, and not just snogging. Snogging and, well, more than snogging. A lot of snogging and more than snogging. Well, I say a lot, more like a whole ton. Well, I say a ton…"

Rose snickered. For a self-proclaimed genius, sometimes he could be so thick. "Perhaps you didn't notice whatever it is because you were a bit distracted when we were doing all that really brilliant snogging and shagging?" she suggested with a smirk.

He turned and stared at her thoughtfully, apparently considering her words.

"Ah," he responded after a moment.

"Yeah, ah." She walked up to him and took his face in her hands.

"Doctor, focus," she said. "What is it? What did you miss?"

"Rose," he answered slowly, "you are full of artron energy. Artron energy. Anyone who travels in the TARDIS picks up a tiny bit of it, but with you…. You have much more in you than would be typical for someone who had simply traveled in the TARDIS."

"Yeah. Okay," she said. "So what is artron energy?"

The Doctor looked surprised. "Oh. Haven't I ever told you about artron energy?"

"No," she told him flatly.

"Oh," he said, taken aback. "Really? Are you sure?"

"Yes, I'm sure. Really."

"Rose, artron energy is one of the types of energy that is in the heart of the TARDIS. It, along with Huon energy and the energy of the Vortex are the primary types of energy that power the TARDIS. Huon energy is extremely rare and toxic. Artron energy, on the other hand, has enormous healing properties. It is one of the components of regeneration energy. In sufficient quantities, it could trigger a regeneration in a Time Lord. In fact, on Gallifrey, if a Time Lord was having trouble regenerating, he was given a large dose of artron energy."

She stared at him as some pieces of a long unsolved puzzle started falling into place.

"So," she said quietly, "when you took the Time Vortex out of me, it was the artron energy that triggered your regeneration?"

He looked at her, considering how to answer. "Yes," he said finally, "that's ultimately what caused the regeneration. Well, at least it's why it happened so quickly after I took the Vortex out of you. Taking the Vortex out of you would have caused me to regenerate, but the artron energy made it happen almost immediately."

"And you knew that would happen, didn't you? You knew that when you took the Time Vortex out of me it would trigger your regeneration."

"Yes."

"And you did it anyway."

"Yes." When she stared at him, he continued. "I couldn't lose you. I had thought you had been killed by the Anne Droid on the Game Station, and then when I found out you weren't …. That's why I sent you home. To keep you safe. I was certain you would die if you stayed with me. And then you came back and saved me…." He swallowed thickly. "I couldn't lose you. Not if there were something I could do about it. And I'd do it again."

"But… but now you can't regenerate anymore."

He looked at her evenly and didn't reply.

Her eyes widened. "No," she said, shaking her head. "No. I won't let you."

He shook his head and looked troubled. "Rose, it's not a possibility anymore. You've been living with this for so long I don't know what it could do to you even if I tried. It certainly doesn't appear to be hurting you, quite the reverse in fact."

"What do you mean?"

"Your health. Your ability to heal. The fact that you don't have any damage to your chromosomes even though you used the dimension cannon so much…." His voice trailed off and he stared at her. "The dimension cannon…." He said it like a revelation.

"I thought you said the dimension cannon couldn't do this. Remember? I asked you about it that first time we came to Cardiff together in this universe. You told me that it couldn't cause this."

"It can't. And it didn't. The dimension cannon would cause chromosomal damage, not heal it."

"Then what…."

"The artron energy had to have been in your body ever since you became Bad Wolf," he said. "I thought I got it all out when I took the Vortex out of you, but I must have missed some. Over the years it must have been lying dormant in your body until you started using the dimension cannon. The stress of using it must have somehow activated the artron energy and increased your body's ability to heal itself. Kind of like the way antibodies work in your body when you get exposed to a virus. The stress of being exposed to a virus triggers the production of antibodies which then assists in your body's ability to identify and attack the virus."

"So the stress of using the dimension cannon…" she said.

"Triggered the artron energy to activate in your system and helped your own body to heal you," he finished.

She was silent for a few moments while she pondered what he had told her.

"Doctor," she said eventually, "if all this artron energy in me is making me heal like this, is that gonna make me… like Jack?"

"How do you mean?" he asked.

"You know," she said hesitantly, "not… not able to die."

"Oh!" He shook his head. "No."

"Are you… sure?"

"Absolutely sure."

"Doctor, you've been wrong before about things," she reminded him. "How do you know you're not wrong about this?"

"Rose, Jack is immortal. A fixed point in time and space. To a Time Lord, he literally looks and feels… wrong. I eventually got used to it, but when I first saw him after he became immortal, he made my skin crawl. Believe me, I would know if you were like Jack."

"Well, that's a relief," she said. Her body relaxed, releasing a tension she didn't realize she had been holding in. "So what do we do now?"

"There's nothing to do," the Doctor replied. "If it was going to hurt you it would have done so by now. And trying to take it out would probably do more harm than good."

"What about the TARDIS coral?" she asked.

"Somehow the coral was able to respond to the artron energy in you when it wasn't able to respond to any of the energies in this universe." He looked at her thoughtfully. "It must be because you have both the energy from our home universe and this universe in you. Somehow the combination was able to bridge the gap for the TARDIS coral and it was able to absorb it."

Slowly he grinned at her and she grinned back.

"Doctor, it's still alive."

"I know!" he said excitedly. He picked her up again and twirled her around, and this time when he set her down, he kissed her properly.