The Doctor just stares at Rose/Bad Wolf for a moment, his mouth hanging open. With a shake of his head he regathers his senses enough to utter one word. "What?"
Rose looks at him, clearly puzzled. "What d'ya mean, what?"
"What you just said, about regeneration energy. What did you mean about controlling it?" the Doctor asks.
"I've no idea what you're talkin' about, Doctor," Rose replies, shaking her head as she speaks.
The Doctor looks more closely at her and notices that her eyes are no longer glowing. Bad Wolf has retreated again, it seems.
"Your little experiment with Bad Wolf doesn't appear to be working," the Doctor informs her. At her questioning look, he goes on to explain about how Bad Wolf had told him to find a way to control regeneration energy. "But it just can't be done, Rose," he finishes, running his hands through his hair in frustration and starting to pace back and forth.
"Well there must be a reason why she wants you to control the energy. What else can you use regeneration energy for, other than healing yourself?" Rose asks him. She feels slightly guilty that Bad Wolf kept that conversation, and the reason for it, from her.
The Doctor paces some more, considering her question. He suddenly stops and spins around to face her, a big grin nearly splitting his face in two. "Rose Tyler, you're a genius!" he exclaims, hitting himself in the forehead with the heel of his right hand. He skips over to her, grabs her by the hands and dances her around the console.
She throws back her head and laughs, not knowing what she has done but pleased that she has made him happy.
He eventually dances them back over to the jump seat and helps a now breathless Rose back onto it.
Once she has caught her breath Rose asks him what he has figured out.
"You asked what else regeneration energy could be used for. And that's it – that's the answer!" the Doctor exclaims excitedly, bouncing on the balls of his feet.
Rose laughs at him, her tongue peeking out of the corner of her mouth. She finally grabs his hands in an effort to calm him down. "You're not making any sense at all!" she laughingly tells him.
Never one to miss an opportunity to impart his knowledge, the Doctor calms down, switching into lecture mode. He sits beside Rose on the jump seat, angling his body so that he is half facing her.
Taking a deep breath the Doctor launches into his explanation. "Not much is known about where the ability to regenerate came from. Time Lord history indicated Rassilon may have had something to do with it. At any rate, all we knew about it was that Time Lords had 12 regeneration cycles, with each cycle lasting up to a few hundred earth years, barring accident or other unforseen circumstances. With each cycle every cell in the entire body changed, regenerated. Hence the change in appearance and personality. But the memories remained intact, if a little scattered at times!" The Doctor pauses for a moment to see if Rose is following him so far.
At her nod he continues. "One of my lecturers from the Academy was experimenting with regeneration energy. He was the one who discovered that excess regeneration energy could be siphoned off into a matching biological receptor."
Here he waves his right hand at her, giving her a grin. Rose just grimaces, that hand still gives her the creeps!
"Anyway," the Doctor goes on, "your question reminded me of something he was working on when I…, left. He was looking for other ways to store excess energy instead of having to siphon it off into a biological receptor. Not everyone has a spare hand lying around, you know!" he says with a wink.
"So did he find a way?" Rose asks him excitedly.
"I don't know. I never got a chance to ask him. The last time I was there we were in the middle of a war…." He trails off, the pain of his memories evident on his face. Rose takes his hands and pulls him to her, her arms about his waist and his head resting on her shoulder. She rubs one hand up and down his back, whispering soothing nonsense sounds to him.
The Doctor accepts her comfort for a few minutes before pulling himself together. He sits up slowly and gives her a weak smile. "I'm sorry, I thought after all this time it would be easier to deal with, but ….," he breaks off as Rose interrupts him.
"You don't have to apologise to me, Doctor. I'm just glad you're sharing your feelings with me, instead of bottling them up inside. Now, come on, tell me this theory of yours," she says with an encouraging smile, nudging him gently with her shoulder.
"Well, you saw what happened with me that last time, when I healed myself using the regeneration energy. His idea was that the energy doesn't have to be used on yourself, that it could be stored and used to rejuvenate, revive or recreate other living things, be they animal, vegetable or mineral. And I think I know a way to control that energy," he finishes, his trademark smile back in place.
Rose lifts her head to look him in the eye. He sees the flash of gold just as Bad Wolf speaks. "And you made it just in time, Time Lord. We're there!"
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"We're there?" the Doctor repeats, momentarily stunned.
"Yes, Doctor. New Gallifrey. Come and see for yourself." Rose/Bad Wolf hops down off the jump seat and heads for the doors, beckoning for the Doctor to follow her.
He reaches her side just as the doors open. What he sees leaves him speechless.
They haven't landed on the planet as he expected. Instead they are hovering above it, out of reach of the gravitational pull. There is nothing recognisable about the planet below, no land masses or seas, just a mass of swirling clouds of gas. Gases of different colours cover the whole planet as far as the eye can see. There are blues, greens, reds, pinks, oranges, all the colours in the spectrum are represented.
And then it dawns on him. That's not gas down there, its regeneration energy. The regeneration energy of the Time Lords who gave their lives to end the Time War and save all of creation.
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