As the Doctor regenerated into his 11th form, he felt a strange entity enter his body. This foreign force scared him. Nothing should be able to pass through those mighty, if wooden, doors, especially as they were currently floating through the Time Vortex. Then he felt something (or someone) inhabit his mind.
"Hello, I'm The Doctor. Wait, no I'm not. Yes, I am. Oh, hello Rose. Rose!" he rambled, wrapping his arms around said person. Rose stiffened in his hug and he stepped away from her. "What's wrong?" he asked, concerned, forgetting about the whole, someone/thing has invaded my mind and we might not be completely safe situation.
"Who are you?"
"I'm The Doctor."
"No, you're not. My Doctor has big ears and ... and he looks nothing like you. You're just a thin strip of nothing!"
"Thanks."
"What did you do to my Doctor? Where is he? Give him back to me!"
"No. Rose, I'm right here. You saw me, I changed back there."
"All I saw was a bright light and ou replaced him. You must have used a teleport or a transmat or ... or ... something else."
"All of that light was my regeneration energy."
"You're what now? Anyway, listen to me. I'm not scared of you. I've seen Daleks and Gas Mask Zombies and even Slitheen. Oh my God! Are you a Slitheen?"
"I am not a Slitheen," he replied calmly.
"Well, of course you're not. What was I thinking! Slitheen hosts have to be large. You certainly are not!"
"Again, thanks. Ok, just to prove it. When I first met you, oh so long ago now, down in that basement, I said one word to you. Just one. 'Run!' And we kept on running, didn't we. Run run running. And that one time we had to hop. Do you remember that? Hop hop hopping. No?"
"That doesn't prove anything."
"Do you want me to change back?"
"Yes."
"Oh."
"Can you?"
"No."
"Oh."
"Do you want to leave?"
"Do you want me to?"
"No! I just thought that ... anyway, let's get you home. Let's say, December 24th, 2005. Christmas present."
*DOOWEEDOOOWEEEEOOOO*
The mysterious entity had almost taken over the Doctor's body completely. In the meantime, the Doctor had almost forgotten about the lost soul currently inhabiting him.
