"Doctor?" I called blindly into the TARDIS. I had just been in the library, looking for a good read, and I had came across a really dusty old book with the title worn off the side. When I picked it up to see if the title on the front was visible, and a picture fell out. The picture was of a very pretty girl with dirty blond hair and brown eyes. Ordinary enough, unless you know the Doctor. You see, in all the time I've known the Doctor, he's never carried, or owned, a picture. Not of anyone.
"Yeah, in here Emily!" I heard from somewhere to the left, so I started walking blindly in that general direction. I found the Doctor sitting in a fairly small room with four offwhite chairs and a wooden coffee table. I sat down in the chair closest to the Doctor, who was working on some sort of circuit or something. "Did you need something?" He asked, not looking up from what he was doing.
"Well, I was in the library, you see, and I ran across this old book, and it looked really interesting, so I picked it up. Who is she, Doctor?" I asked, handing him the picture. I watched his expression shift from concentration on his work to some sort of deep sadness. "If...If it's something that you don't want to talk about, that's fine. I mean, I shouldn't've snooped anyway."
"No, no. This is Rose. Rose Tyler. She was my companion for awhile, but she's gone now." I looked at the Doctor in shock. "No, no! She's not dead. No, she's fine. Parallel Universe, with me."
"With you, Doctor? How?"
"Well, it's really complicated. But, basically, one of my later companions, Donna Knoble, ended up accidentally creating a half human half Time Lord me."
"And he's with Rose?"
"Yeah, he is." There was that sadness again, just in his eyes.
"You loved her, didn't you?"
"Yeah, yeah I did."
"And she you?"
"Yeah. But now she's able to live a life with me, happily. And I'll age, and die. She has a me, but a me that she can settle down with."
"But you were left alone."
"I always am, in the end."
"You've got me." I said, smiling.
"Until you get bored of traveling."
"That's never going to happen."